GFX is a good acronym. It certainly made me think of "graphics" right away.
.BIZ is not exactly on-fire, but it's still a fairly solid extension.
As a cheapskate reseller, I would probably give you a couple hundred bucks ($200) right now. To a possible end-user sale or graphics business, this name has excellent value in my opinion. I could see it selling for $1K-$2k... in a situation where the buyer is looking specifically for a graphics related domain.
Nice name. Good luck!