Lurch - It only cost me $600 to have the guy spray it, that included the cost of the gel coat. He gave me a deal on the gel coat as it was getting old and he wanted to get rid of it. I dit the prep (basically just sanded with 120 grit and wiped down with Acetone), and I will do all the post spray wet sanding and polishing. Took him about a day.
The additive that ABL is talking about is Duratec. It adds gloss to the gel coat making it easier to get a nice finish. Whoever sprays it for you will probably already know about this stuff. You can read about it at:
http://www.minicraft.com/Retail/duratec.htm