I'm looking into buying a 1999 Tahoe and the guy says the steering gearbox needs to be replaced because the Tahoe tends to pull to the right while driving (more so than would be expected on a normal road) as though it needed a front end alignment, but it doesn't need a front end alignment.

He claims this is supposed to cost $123. My wife hasn't found a new gearbox for sale online for less than $200. How much can I expect to pay for this job? (If you give me a price, tell me if it's parts & labor or labor only. I know you can usually save a few bucks by buying the part yourself.)