There are better things to spend a student loan on, and hpi on a 5k car is pretty daft anyway.
Yes there are a lot more things to go wrong on mk4's, and the parts are more expensive.. but that's the way it is with modern cars. You need to ask yourself if you can afford to own it, not just afford to buy it.
In 3 years of ownership my mk4 has cost me around 2k in repair bills, around the same in mods. Then add a service every 5000k, tyres, insurance, tax... hard slog for a student.