My advice (owing to recent experience) would be to check that when the engine is warm, it doesn't sound like a diesel on idle. If it does that'd be a shot dephaser pulley, very expensive job!
See what I mean from YouTube to get an idea of the sound. I'm in this situation myself! £170 for the part, and has to be done with belts / kits
Also - check climate control switches between hot and cold OK (common fault), seat handles work, headlight washers (not so important), and obviously all the standard things you'd check when buying a used car.