Upvote:1
While you get a more concrete answer, here is some info.
Rio is out of the way (its farther from Bogotá than BA is), unless you explicitly want to visit; it's a 3-hour flight (or 48-hour bus) from BA and it will not be particularly cheap. And then its not like Manaos is close to Bogotá...
You could fly to Bolivia or Perú and then try to get to Bogotá by land; but be warned that transportation in Bolivia is an adventure in itself. You could also consider a bus or flight from Buenos Aires to Santiago and then make your way up.
All said, I don't think you can make that trip a lot cheaper. Bogotá is 7000km away from Buenos Aires (for comparison, Perth is 4000km away from Sydney).
Upvote:1
Flights within South America are notoriously expensive. Occasionally, you might be able to get a deal, but you'd have to keep monitoring ticket prices. While one-way tickets seldom can be had on the cheap.
There is no easy overland route from Argentina to Colombia, but it's certainly doable, and you're doing it yourself in reverse already. The typical route between the two is Colombia to Ecuador to Peru, then to Argentina via either Bolivia and Brazil or Chile. But, this is the journey you're already taking.
If you want to avoid this itinerary going from BA to Colombia, some options are: