Seems like a real cheap price for an aftermarket nsx flywheel. 7 Pounds seems very light. I'm not familiar with fidanza.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7975769694&category=33732
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7975769694&category=33732