I like the term "Accuracy 'Smith".
He may or may not have a pressure flush system for chambering. If not, it's a laborious process. A big chamber may take 8 hrs or so, involving pulling and cleaning the reamer and chamber 100 or more times. Small chambers might be 2 - 3 hrs, and 40 - 50 pull / cleans.
At any rate, I think that $500 is a fair price for a good job. If the action requires a cone breech and extractor cut, add ~ $100. Labor to install a brake could run from $50 for a concentric brake to $100 - $125 for a timed brake. both prices could include some tapering and barrel O.D. matching.
Any rebarrel should include test-firing and caliber marking. Add that to disassembly, set-up, machine time, headspacing and reassembly and it would be easy to have 20 hrs in it. About $25 / hr.
I've only done a few rebarrels for myself and my family, and have discovered that I'm slow, so I estimated these times from a statistically small number, knowing that it usually takes me longer than 20 hrs total time.
+1 on the pay once.
Good luck, Tom