Japanese Music Bargains

A lot of old/trad Japanese music is available here in 100 Yen shops (the equivalent of Pound Shops, except that Y100 is more like 50p) and CD shop bargain bins. I got a complete set called Folk Music of Japan - 11 regional CDs - for JPY100 each (that's about 50p), and all excellent and raw music (not synthesised or orchestrated). Today in a supermarket I got a Columbia label CD (Old Melodies (No 40 in a series)(JPY1000 (about GBP5)), and a Keep label DVD of Japanese Festivals (part of a 6DVD festival set)(JPY500 (GBP2.50) each). I'll check out the quality and report back (I lately bought two of the World Heritage Series DVDs here - England and Kyoto - and they were very bad indeed, so let's see about this new lot). Anyway, the cheap, high street, non-specialist availability of this material is something visitors might want to take advantage of. I guess it's down to market size and Asian production prices. What it might signify is that (non-copyrighted) folk/traditional music is so mainstream/popular in Japan as to merit mass-production in China. Or is it the opposite - an imbalance of production over demand? How do these Y100 shops work? Certainly the labeling is specific to the Y100 shop brands, and includes the Y100 price printed on the sleeve.