Well, the road to a sub $300 3D printer is one filled with perils (both for buyer and seller), but the reward is certainly enticing for each as well. Many of the Repraps get close, but it seems like there's a pretty hard $500 floor to the prices that only a few kits in development seem to have a hope of getting below. Without a different method of printing entirely or designing specifically for economy of scale (and having the rescources to actually take advantage of such a scale) there's very little hope of getting to the magic price.