The $50 spending requirement does seem rather high for the average buyer.

Not to be overly argumentative, but two of the shops that have been pointed out as treating the vendors more fairly, PoserPros and 3DCommune, both went down the tubes.  In the case of 3DCommune at least some vendors didn't even get paid at the end because the money intended to go to them got spent before they could be paid.  People seem to be assuming that it's easy and cheap to run a site like Rendo, and that the people who run the site are wallowing around in piles of cash earned off the sweat of the vendors.  This just may not be true.