http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2403745072
This auction is for a set of 4 brand new 2003 NISSAN 350Z, 18" x 8" 6-spoke aluminum-alloy wheels. They are brand new with 0 miles on them.
The reserve price is set at half of the replacement cost.
I believe the wheels will fit a 300zx:
http://www.zcar.com/forums/read.php?f=3&i=90899&t=90899