You should really consider price floors for certain categories (take crowdspring as an example). For example, there's someone on your site offering 1 BTC (~$12 USD) for a logo...I'm not even a designer and I know that's an awful price.
Sites without floors tend towards high-volume, low-quality projects listed. I am not saying you should have market prices, but having some reasonable floors will give the site better quality.
Sites without floors tend towards high-volume, low-quality projects listed. I am not saying you should have market prices, but having some reasonable floors will give the site better quality.