I'm like BladeZealot, rarely go to GA after they changed. I had bought a couple guns off there but haven't since. I'm not completely thrilled with GB, would just as soon know a guy's price, they sometimes start with a stupid opening bid and most of the time the item won't sell unless you go for the "buy now" price anyway.
I have bought and sold on Gunbroker maybe a half a dozen times total. Never a problem, just the pains of shipping ammo legally as well as dealing with FFL if necessary. But it is a great place to find an item at a great deal if you can have the will power to wait! I have bought a 458 Socom and a 5.7 pistol (at different times) on Gunbroker. I was able to save about 30% on both, not including the extras that came along! I cruise Gunbroker almost as much as I cruise here! I have sold a Remington 700 VSSF II on there and a 223 WSSM upper on there as well. I have bought ammo and reloading supplies there too.
gunbrokers fee system is about like rocket science... they charge you x% for items under $20 dollars then they add that plus another x% for items under $100. For items over $500 i think its a flate fee plus x%.