When I was looking for an extra set of 18" wheels for mounting winter tires, I found the following sources and prices, which some of you may find helpful.
These were the best prices I could find:
has 18" new silver OEM wheels for $189@.
They also have new polished 18s and 20s at considerably higher (but probably very competitive) prices.
has USED 18" silver wheels. They had several sets of four. One set was priced at $92.90 per wheel, and another was priced at $106 per wheel, with FREE SHIPPING! This is apparently a salvage yard in the Detroit area, so verification of the wheels' condition would be important. They also had 20s in the $250 range.
For some reason, it's not allowing me to include the entire address above, but I just clicked on it and it brings up the proper site.