Joseph M. Horton, of Pasadena, is the former owner of the now-defunct Around The Clock Locksmith.
A judge in District Court in Annapolis found him guilty of forging the signature of a woman on her credit card receipt after she refused to pay for his inflated services.
Officials say Horton quoted a woman $250 to unlock her car during a snowstorm, then charged her $1,000 after he opened the vehicle.
She refused to pay.
Horton was sentenced Friday to 60 days in jail, followed by three years of supervised release.
The Capital of Annapolis reports that Horton is appealing, and that his lawyer says none of the allegations represent a crime.