As others have stated don't worry too much about the mileage that is on it, look at the overall condition of the vehicle and the "service history" which comes with it. My 200tdi has 270k on the clock and is still going strong, drove to and around morocco this year with no issiue, and would happily get in it tomorrow and complete another trip. That has no official service history and I do not even own the service book, but I have a folder of every penny that has been spent on it in the last 10 years of my ownership totaling more than I care to add up!
If it is a private sale and comes with a large folder of receipts and invoices for parts from a bloke with oily hands, I would trust the vehicle far more than one from a dealer with a fully stamped up official service book. But on the flip side, I would still be wanting to give both vehicles a thorough check over to build up a full picture of the current condition and how well it has been looked after previously.
When looking at the condition it is the little things that help to build up the bigger picture. Look for the obvious, like rust and chassis/bulkhead condition, but also check little things, like how recently the prop UJ's have been greased etc. to get a complete picture of the general maintenance which has been carried out.