I find lots of wheels at wrecking yards, craigslist, swap meets. I haven't bought any new ones. But Panasports has them.

The wheels mostly come from Toyotas, and Datsuns like the 280Z. Plus vintage wheels from Mustang and Camaro six-cyliner models.

Look for 4.5" instead of the 114.3 metric conversion. Most were made as 4.5" bolt circle wheels. Only the "sport compact" crowd in USA calls them metric.