thats what a written estimate is for...i believe if they dont give you one that you sign off on, then they are SOL, and any work over 100 dollars requires an estimate, meaning they cant put a mechanics lein on the bike if they all of a sudden feel like wanting 500 dollars for what you thought would be a 100 dollar job. but please verify this, i do not know the finer details of the estimates, but i know they are mandatory nowadays for "consumer protection"