wow, I am very sorry to see this. It does look pretty bad. If I were you I would either:
a. Cheapest option: Repairing the wheel ($150ish as crash mentioned.)
b. Regular option: Get the same single OEM wheel. You can get them on ebay/craigslist or Nissan dealership etc. This one is for a whole set
eBay Motors: 370Z 19INCH WHEELS (item 280313687853 end time Feb-22-09 11:57:50 PST) but you get the idea.
c. Expensive option: Get a new set of Volks from one of our sponsors