Edit - One more item. You must have content outside that forum to bring
SEO traffic. Consider an interesting blog page with links regularly to items for sale. No content = no traffic.
I'm harping on this because I can't tell you how many of my motorsports customers seem to think that just because they have items for sale on the INterwebz, that customers will magically flock to them. "Hey bud, there are 132,357 people selling Ate Blue online right now. Why would they buy that can from YOU?!" If you don't have a good answer, the real answer is "they won't"
Here are some questions to ponder on and the answers will drive your marketing plan.
1. Why will people go to this forum vs. other culinary forums?
2. What can you do to provide a more interesting buying experience?
3. What value are you providing over other sites (both information and commerce)?
4. Who (and be honest) is your target market?
Hope this helps!!