Hi and welcome to the site. The Golf sounds ok but depends on the money really. Faulty speedos is not a common fault as far as I am aware. There is a section on here for what to look out for in the Mark 3 section but look for rust in areas such as the top of the windscreen, bootlid and bottom of doors and sills. Check the jacking points underneath as the original jacks are useless and when not used properly they bend the points and mash up the sills. Check the electrics and non working windows are a common issue as well. Also check all the carpets as water leaks are pretty common. All faults are easily fixed with help from this site. To check the mileage of the car on the VOSA website then get the mot number and the website will give you the history of mot's. Will verify mileage and show what has been done to the car. Costs nowt as well. Good Luck Cheers Deano