How did the Soviet Union support the development of their atomic bomb in 1949?

Op's comparison of value is a red herring. Cost of living was dramatically lower in the Soviet Union than in the U.S., even at the time, so raw exchange rate creates a completely meaningless value comparison. Only for international purchases outside the Soviet Block would it have any meaning.

It's important to realize that the Hiroshima and Nagasaki bombs, though both "atomic" (a terrible descriptive, as all of chemistry is atomic energy and we're really talking nuclear energy in regards to fission and fusion bombs), were very different beasts. One was a dead-simple uranium bomb requiring no testing at all; while the second was vastly more complex, and when finally tested as Trinity not all the designers were confident of success.

So what is the key significance of the differences? Fuel supply. The Little Boy uranium bomb required enriched uranium as fuel, which prior to key engineering developments in late September 1945, could only be produced, even with the vast resources of Manhattan, at a rate of about 1 bomb every 6 months. The scientific and engineering requirements for Little Boy were solved quite early at Los Alamos; and then the team simply waited for sufficient fuel to be available.

However every uranium-fueled atomic pile rapidly produces sufficient plutonium fuel for a Fat Man bomb every 7 to 10 days. However the Fat Man bomb design was soon realized to be far more complex than for Little Boy. This is where the bulk of the Los Alamos effort was spent from 1943 to August 1945.

Brief aside: The question is often asked: Why drop the Nagasaki bomb? Wasn't Hiroshima sufficient? The presumed answer is no, due to the Japanese refusal to answer or acknowledge the surrender demand following Hiroshima. There was no secret about the difficulties and time requirements for enriching uranium - it's the first concern encountered by every scientist, in every national bomb project, and why Iran still hasn't got a bomb. (Their centrifuges used for enrichment keep blowing up for mysterious reasons.) Nagasaki sent a very clear message to every physicist and informed politician around the Globe: "We SOLVED the uranium enrichment problem. Take that!" And that is why Hirohito forced the War Cabinet to surrender.

Now look at the initial test history of the Soviet Union:

1. RD-1 - 29 August 1949: claimed 22 ktons (same as Nagasaki) but believed to be under 20 ktons (more like Hiroshima).

2. RD-2 - 24 September 1951: 38 ktons - even greater than Nagasaki.

This initial speculation on my part was incorrect. Classified documents released in the 1990's confirm that The RD-1 nuclear test in 1949 was an implosion-type plutonium bomb very similar to Fat Man. However the Soviet development continued for many years after WW@ to be constrained by access to uranium, as noted in the update below. Their uranium access was so constrained that even plutonium bomb development and test were limited by it.

The obvious conclusion is that the Soviets completed a simpler Hiroshima-type bomb (despite Beria's insistence and claim that it match Nagasaki) in 1949; and a much more complex Nagasaki type plutonium bomb only 25 months later. A definitive determination would likely be possible by inspection of fallout from the two bombs, but I haven't found yet that analysis online.

Remember the main obstacle to a Hiroshima-type bomb is just the time required to enrich sufficient uranium. it's not a complex device. Los Alamos didn't even bother with a test, their confidence was so great.

Finally, I have doubts that any intelligence received from Fuchs (or others) had a significant effect on the Soviet timeline. It's like being given the answers to a test - but betting your life on your understanding. What a coup it might have been for the entire Soviet team to blow itself up in an "accident" due to planted incorrect intelligence! All such received intelligence really does is give you an answer crib to check your own calculations against. That's useful, but not critical.

Update:

Here is a very good summary of the early Soviet bomb development. My supposition above about RD-1 is apparently incorrect; it was a plutonium bomb of design comparable to Nagasaki. Rather, speed of Soviet bomb development seems to have been constrained by uranium supply.

Some excerpts, [with my comments in trailing brackets]:

Alexei Kojevnikov has estimated, based on newly released Soviet documents, that the primary way in which the espionage may have sped up the Soviet project was that it allowed Khariton to avoid dangerous tests to determine the size of the critical mass: "tickling the dragon's tail," as it was called in the U.S., consumed a good deal of time and claimed at least two lives; see Harry K. Daghlian, Jr. and Louis Slotin.

One of the key pieces of information, which Soviet intelligence obtained from Fuchs, was a cross-section for D-T fusion. [D-T stands for Deuterium-Tritium, so this is only relevant to fusion, ie hydrogen, bombs.]

The single largest problem during the early Soviet project was the procurement of uranium ore, as the USSR had no known domestic sources at the beginning of the project. The Soviet F-1 reactor, which began operation in December 1946, was fueled using uranium confiscated from the remains of the German atomic bomb project. [The speed of Soviet bomb development seems to have been tightly constrained until discovery of the Kazakhstan uranium deposits in about 1947.]

In regards Soviet uranium supply prior to ~1970:

The American administration knew that uranium wasn’t mined in the Soviet Union. That was the main factor in their hope, which was dominant after 1943, of an atomic monopoly.

On 8th December 1944, Stalin signed GKO Decision no.7102ss (‘ss’ meant ‘completely secret’). In accordance with this decision, all the programmes for mining and processing uranium were transferred from the commissariat for non- ferrous metals to the commissariat for internal affairs (NKVD) and put under L.P. Beria’s control.

A transformation in the production of uranium was achieved. By the end of 1945, Combine No.6 had processed about 10,000 tonnes of uranium ore to produce seven tonnes of uranium concentrate. In 1946, 35,000 tonnes of uranium ore were processed. By the end of 1947, Combine No.6 consisted of seven uranium enrichment plants receiving ore from eighteen mines. 176,000 tonnes of uranium ore were processed, producing 66 tonnes of uranium concentrate. This guaranteed the production of almost 25 tonnes of uranium metal. In 1948, the production of uranium concentrate doubled. But this still did not satisfy the demands of the industrial reactor which had been built not far from the Urals town of Kyshtym. The greater part of the uranium which was loaded into this reactor in the spring and summer of 1948 consisted of uranium trophies found in Germany in June 1945, and from the established uranium mines in Czechoslovakia and Germany. Only in 1950, when the Leninabadsky combine was processing more than 600,000 tonnes of uranium ore every year, was the decisive significance of imports reduced. At this time, 18,000 people worked at Combine No.6, of whom 7,210 were prisoners.

Note that naturally occurring uranium is only about 0.72% U-235, the fuel from which uranium bombs are made. So not only must the uranium ore be smelted and refined to pure uranium; but it must then subsequently be enriched to between 3.5% and 4.5% for (most) reactor use; or to roughly 85% for weapons use. To produce the 64 kg of enriched uranium used by the Little Boy bomb then required 64 kg * 80/0.72 = 7.1 tonnes of refined uranium metal; 17.8 tonnes of 40% uranium concentrate; and about 35,500 tonnes of uranium ore of the quality available from the Tadjikistan-Uzbekistan-Kirghiz mines. All hauled by mule, 70-100 kg at a time, over the area's rough mountainous terrain.