I've been using goozex for about 6 months now, and its great.
First off, the person who is recieving the game is the only responsible for paying the $1 transaction fee. Small price to pay for the convience.
Yes, the "seller" has to pay the shipping, but $5?!? no... I ship all my games first class mail for $1.65. Again, not too bad.
On top of everything, you get a damn good market price for the games... new games usually run 900 - 1000 points (100 points is equal to $5) so thats 40 - 50 bucks in credit.... much better than trading it into a gamestop for $20 a week after it comes out.
The older games depending on rarity or demand, are mostly 100 points (or 5 bucks)
Last week I traded Resident evil umbrella chronicles for 900 points ($40) and and with those credits I've gotten 4 games.
Once a game got lost in the mail to me, and after keeping in contact with the seller, and believing he sent it, We contacted the admins and I recieved my points back, the trade credit, and he got to keep his points as well. Very quick, nice, and respectful.
The only downside to the site is having a bunch of points and not having the immediate opportunity to get the game(s) you want, but the wait is generally shorter than you think.... Like right now I am 67th in line for mario party 8, but in the last week I've gotten a few emails saying I had the opportunity to get the game, but not enough credit, so it continued down the line to the next person with available credits.
I can't recommend the site enough.... hope this helps some of you. Oh, and if anybody wants to try it out, the referel would be awesome.