Upvote:3
Money exchanges bureaux are not popular in the US, and you will have really hard time finding ones outside the airports and major tourist cities (San Francisco, Las Vegas etc) - and even there you'll only find them in major tourist spots.
Because there are so few of them, and they're limited to locations listed above, where the costs of renting a business space are quite high, I don't think what you're asking is possible at all. Those I've seen had a really large spread, often exceeding 20% or even more.
Banks in US can also do currency exchange, but not all branches will do this. And their rates, when I tried to purchase foreign currency from them (Wells Fargo and Bank of America) were very uncompetitive comparing to the rate they'd give me when getting money from an overseas ATM.