When you build a website (for example, a site to connect sellers with buyers) which mostly relies on user generated content, how do you tackle with the below situation?
"User will not be coming to your site when there's less/no content. But, Content will not be generated when there's less/no user."
What would be the approaches to grow content/user base?
This kind of questions gets asked a lot here. The common response is "Fake it." Follow reddit's lead and generate content yourself until others catch on. You also might try mechanical turk, though I have no experience with this myself. Also, post a link. You'll get better advice if you supply more detail about your site or the actual site to look at.
If the content/information exists elsewhere but just needs aggregation, you need to massage/import in order for it to be useful to you future users - so take the plunge and import it so that users will find your service useful, even if this costs you some money up front!
If it's a matter of requiring users to generate your content for your site (like www.reddit.com), then definitely as other users have said... fake it.
Sign a few sellers, and give really good offers for them to use your site. Then help those sellers advertise. Do it again. & Again
Keep building the snowball until it's big. It's not easy, but that's one possible one. It should much much easier nowadays with all the social networks, but nothing is easy. Just a lot of hard work and convincing.
I actually have a track record of promoting conversation traction in online forums. But I don't know how those principles would be applied to the kind of site you are asking about. I am interested in getting a better understanding of such things in part because while I seem perfectly capable of increasing traffic (and thus membership) on someone else's discussion board where there is already a certain number of members (but discussion is anemic), my own email lists and websites lack traffic (and members). :-/