Ron - I agree that pressure testing is a good idea, and I also use a bottle of star san for this.
However, IMO a leaky poppet or a lid is typically a pretty simple fix and I wouldn't walk away over a minor and fixable leak.
I've heard of bends on the keg mouth that don't allow a seal, but I've yet to encounter a leak in my kegs that can't be fixed easily - poppets and gaskets, mostly, though I have also replace one or two pressure relief valves.
In the last 60 days or so, I've been quoted $60 and $65 a keg for used kegs at the LHBS and the gas supplier. This is a huge jump from the approx. $30 they were going for last summer.
For $25 a piece, I'd grab them (assuming there's no major damage). And, I'd recommend at some point stocking up on a few spare parts - gaskets (McMaster Carr is the place) and poppets, for sure.