use Ubitex.org to do your match ups.
Is this something that you actually do? I've been watching Ubitex since it opened, and honestly it doesn't seem very useful at the moment. At the very least, I'd want the ability to tie my prices on there to the prices on other exchanges, like you can in #bitcoin-otc.
For advertising, I was planning on just putting something up on craigslist; maybe mentioning it on facebook too.