I was skimming ebay and came a cross a set of cheap intakes for the Z! The filters are probably cheap, but they are double cone at least. It has a best offer, so one may be able to get them even cheaper!
NEW! 09-10 NISSAN 370Z TWIN AIR INTAKE KIT 3.7L ALL Z34: eBay Motors (item 110569069271 end time Sep-02-10 19:14:22 PDT)