You can't use a mk3 one. You can get a set of Eibachs for under 200quid second hand if you keep an eye out .. if you're on that much of a budget then I really wouldn't bother.
A cheaper option (but harder to find) would be a G60 one as these are a couple of mm thicker, there was one on ebay for 50quid for ages but don't know if it has sold now.