Paint jobs are one of those things that you the owner decides who much it's going to cost. Do you want to spend $2500 or do you want to spend $10,000? It's that simple and this is one of those deals where you get what you pay for. It's not like a part where one supplier is selling it for $300 and another down the road is selling the same part for $210. With paint, if you pay $2500 you will get a $2500 paint job. Nobody is going to give you a $6k paint job for $3k. Not gonna happen...
Joe is spot on with this. There is a lot more to a paint job than what you see. Spend as much as you can allocate for paint. I did mine myself and it came out pretty good considering that I have less than $700 in the whole thing but it is by no means a "show car" job. Regardless of who you choose, as Banshee said, be sure to see more than one car they painted. Also ask to see pictures of those cars during the process.