$10k-$15k is pretty common around here for a show quality paint job, regardless of what car it is on. But after seeing how much work and skill goes into making every single surface "just so"; not to mention facilities, tools, drying booths, and of course the talent for actually spraying a perfectly even coat of paint every time; I can see that being a reasonable price for a flawless paint job.
Years ago, I let a buddy use my garage to paint his car, and he had a friend in the body shop business guide him on doing all the preparation work. I don't know how many hours total they spent, but it was close to 6 months of nights and weekends. Call it 1000 hours, and $10K starts looking more reasonable. He had a pro come in to do the finish coat, which went pretty quick; but then there was more grunt work in buffing it out, and then having to reassemble the car, etc.
Not really relevant, but last night after dinner we walked past a 66 Chevelle that someone was obviously restoring. Beautiful paint job in what I assume was the original color; but there was one bubble on the whole car and it jumped out at me like a pimple at high school prom. I hope whoever owns it didn't hear me point the bubble out to my wife