$2000-$4000 for silverplating.
1) Dent removal? How much is needed? Even small scratches are amplified by plating. The shop must have the correct equipment ($$$) and the skills and experience to use it.
2) Surface prep. Good prep is time consuming and expensive.
3) A shop that has a plater with the equipment to fit your tuba. Not many shops have tanks large enough for the tallest horns.
4) Willingness of the shop to take on the job. I love tubas, but I can make more profit on three saxophone repads than I can on one tuba overhaul with no back ache and in 1/10th of the time.
See examples of the shop's work before you let them work on your horn. Not pictures, actual examples from satisfied customers.
Having seen the work of Joe S., Lee S. and Dan O., you couldn't go wrong with any of those choices if they were willing to take it on. I know Dan just loves tuba overhauls, especially if they need extensive restoration!!!!
Daryl "Who Really Has the Energy to Overhaul Only His Own Tubas" Hickman