Everyone has something to sell or buy, whether It's physical or virtual. If your platform is good (Fees, design, user experience etc.) people will use it.

I don't like the idea of making a user build his own website though, this would require a server etc. If you could make users make their own pages in your site, that would be better, It's also free advertisement for you.

So, If you haven't done so already, I suggest making an thread in the service announcement section.