Music Music Rachel has crowned me king of budget classical CD's. I like classical music and I would buy it even if those CD's weren't so darn cheap, but it helps that I can buy twice as much music for a quarter of the price, compared to popular CD's. I don't know that for a fact, but it seems likely. The physical disk is so inexpensive that software companies send them out as junk mail. Once a producer gets a decent digital recording, CD's can be reproduced dirt cheap by computers.
Most classical composers are dead and their works are in public domain.
European artists, who work for peanuts, relatively. Looking at this from another angle, American production and marketing costs are probably way too high. Most budget classical labels offer only a basic set of works. Naxos certainly seems to be the cream of budget classical, the best of the cheap, with selection beyond the usual. Sony Infinity also seems quite good.