It just depends on so many things. If there was little to no prep required, those low prices are in the right ballpark. I do jobs where I prep for a month and paint in 4 days. The prep is ~90% of the job and the $$.
Here are some pics of the $7500 garages:
Etc., etc... Three double garages with guest houses above, lots of human doors besides the 1927 carraige doors that needed massive repair, all done in oil color-matched to original paint from 1927.
I'm lucky in that I do work that cannot be done by college kids or Mexicans from outside of Home Depot. I lost my ass on those garages but he gave me one of them to use indefinitely as my storage/shop so it's all good.