only advice i will give is 350z aint cheap if you come from a world of hondas or golf and buying wheels for £600 you going to be upset, you can get small wheels and spacers but it will never look as good as a good fitting set of rotas/varrsteon/cosmis if your doing it on a budget, speak with the traders on here they can hook you up with a set of wheel s in perfect sizes and offsets for your Z
if these are what your looking
http://www.ebay.co.uk/itm/18-CRUIZE-190-STEALTH-ALLOY-WHEELS-FIT-BMW-5-SERIES-M5-E39-/280769313590
maybe the 3sdm 0.01 would be to your taste
http://www.3sdm.co.uk/collection/collection-001.htm