Based on the quoted mileage and the age of the Sprinter, it has covered on average just over 30,000 miles a year which is quite normal for a big panel van of its type. We've seen similar-aged Sprinters with much higher mileages and it's the vehicle of choice for all of the supermarket delivery operators, often covering 100,000 miles a year. Keep on top of regular maintenance and there's no reason why it shouldn't see 300,000 miles - there are hundreds of older Sprinters on the road that have achieved and surpassed that but maintenance and regular servicing will be key. If we were looking for a reliable van to do that many miles with, we'd definitely be looking at the Mercedes along with its sister van, the Volkswagen Crafter and potentially the Iveco Daily. The one you mention sounds like a good buy and a fair price if it's in good order.