You should be paying around $470 dollars for paint. Labor is the most expensive component to a paint job so I would say she is hooking you up. 1-1/2 gallon of basecoat, black is a cheap color, unless there is metallics in there. If you use good paint which covers good, then 1 gal should be enough. Clearcoat you'll probably need 1.5 gal. Lets say $220 D403 Jet black for basecoat and $250 923-200 for clear. I'm basing prices off Glasurit. Is she using water base or solvent paint? Forgot to add the primer, the cheapest way is a PCL DTM primer which you can skip the metal etching that should run $100 enough for 2 passes, I don't think you'll need a sealer with that primer, it's very good.