First, is the marketplace at torrentinvites.org legit? Second, is it dishonorable to do such things? Third, how to avoid scams? Fourth, are there alternative marketplaces to have a sense of whether the price is right?
UPDATE I wanted to thank all for the feedback, you made me change my mind and saved my ass from some costly frustrations… good thing I asked here first!
Most trackers have rules explicitly forbidding this practice. If they’re found out (and they will be, it’s not hard to identify if it’s done more than once) you will be banned along with them and the rest of their invite tree. Sorry mate.