Partially because padding shipping to avoid fees is against Ebay policy, and to be honest makes people look dishonest. Not just from the stance of avoiding fees, but for the fact that even counting cost of packaging/handling, etc. for $7 it should at least be priority ( for that much there are a number of free flat rate boxes that could ship multiple games priority). Taking a loss is also the chance you take on Ebay.
Besides you have this listed here, CAG (Cheap Ass Gamer), Sealed games, SHUMPS, NeoGeo, maybe others...that much exposure should lead to decent returns.