It's worthwhile to go through and check what other maintenance needs to be done as well (engine oil, brake fluid, brake pads, rotors, exhaust, brake fluid flush, differential oil, wipers, etc). I bought a used Tundra from a Toyota dealer, and they were perfectly happy to charge me for changing the oil, brake pads, skim the rotors, etc AFTER I had paid for it and used it a month.
Had never bought a vehicle from a dealer before and had assumed 'Certified Used' meant they had done all that, but they hadn't, it just meant they checked and everything met minimum spec.
For your own piece of mind it is good to have all the wear items, fluids, etc replaced or renewed (or for sure know what has to be done and when) on a used vehicle when you get it, so it is probably worthwhile to see what you can negotiate with the shop before you give them your cash.
The other thing is the accident history.