If this is seriously been considered... Awesome!
I'd seriously suggest checking out the full rules list for classified access over at OCF if HWBot is looking for a "template" so to speak.
You'd need to add some people who are trustworthy to the support staff here... Their job would be only to moderate the marketplace sections.
I realize I don't have much of a post count here... But the guys at OCF could vouch for my honesty.
I also have been a moderator of several sections (one being the Buy Sell and Trade section of the largest Radio Controlled based website on the net... http://www.rctech.net )
I do have a bit of experience basically... Just throwing out an offer to volunteer... I've got the time to do it since I'm at the computer 12-15 hours a day.