I don't think a pay-to-post system would be suited at this time either - You can't ask people to pay for something that was previously free unless there is a dramatic improvement in quality. Perhaps it is something that could be looked at long-term (it would be silly to write the idea off completely) but personally I don't believe it's something we should be looking at for the moment.

Paying for extra coverage of a thread (be it highlighting, stickying etc) though is something that I feel could be put to good use for helping with improving the quality of the Market Place as well as helping sellers here at TF.

At the end of the day the only way prices are going to rise is with a rise in quality. As the quality rises as will the prices. Prices can't rise unless they are given a reason to so improving the Market Place on a whole is the first thing we should be looking at doing in my opinion (and are trying to do as previously explained).