I don't think Tom was making an attack at PYSpeed, but maybe should stayed out of the thread. He made some good points. I used to work with my uncles who were high performance mechanics and bought aftermarket parts at jobber -% prices from wholesale distributors. Traditionally the business that stockpiles the most gets the most % of jobber, thus resulting in lower resale prices. Now and days, it seems smaller guys managed to compete by either working exclusive deals (i.e. advertising) or by taking a much smaller cut of profits (taking into consideration smaller overhead expenses).
Also, most big parts vendors sell performance parts and accessories from companies that don't sell to the public. For example, with Japanese cars, you have Greddy, HKS, Apexi, Veilside, Vortech, etc. Most of those parts are ordered through a wholesale distributor, and makes it way down to the vendor. Now if you look on M3Post, most parts can be bought directly from the maker. If you call Vorsteiner, Active Autowerkes, EvoSport, VMR, Rogue, etc you can buy without middle man.