I have a fear of them too. My car is not due until 96000 for its first change (I've had it since 30,000) but it's being done next service along with the tensioner. This will be at about 86,000 miles.
The damage doesn't bear thinking about if it fails. It's nigh on impossible to determine its condition by inspection but you'll probably get away with for the 250 mile ride home.
Ask the seller to discount the price of the belt and labour from the purchase price. This won't stop it failing but will at least let you know you got something in return.
Incidentally, what's the Make and model of car? |