Yeah, two.
1. So you're buying btc, right?
2. What payment method are you buying with?
TLDR: The markets I conduct business there are opportunities when people need to "Cash Out of their inventories". Similar to someone pawning jewelry / valuables for quick cash.
I've recently had need for 5-20 BTC fast. Buying these inventories can give me anywhere from a 10-100% ROI.. depending the situation. Under 10% I wouldn't bother, save items I know I already have buyers/demand for.
I was asked to prove I was the owner of the Steam Account
https://bitcointalk.org/index.php?topic=1132406.0 here.
Check the 1st and 2nd reply's.
He's probably looking for either buying it with paypal or you buy his stuff on steam with bitcoin. Those are the stuff I can think of with this long thread. TL;DR btw.
I am not trading items. Ideally, I'd like to start with PayPal to build a relationship. If my potential partners I verify trustworthy enough I can send W.U. or Wire Transfer.