If the repairs cost over $100, the repair shop must give you a written estimate unless you request to be notified only if the repairs exceed a specified amount.[1]  The shop can charge 10 percent or $10 over the estimate, whichever is greater, but not more than an additional $50 without your authorization.[2]

[1] § 559.909, Fla. Stat.

[2] § 559.905, Fla. Stat.