i haven't got any on my golf but i have used spacers on my other cars and never had any issues, i ran 20mm h + r ones, make sure you get hub centric ones you will also need longer wheel bolts, and on the subject of how much to spend i would recommend spending as much as possible in my opinion its not something to scrimp on really in my opinion, the h + r ones were excellent quality but they are expensive,
it is amazing though how such a small mod can make such a difference in looks,
only my opinion though