You can find non-OEM center caps for pretty good prices online (ebay, Amazon). Otherwise, the new OEM ones are ridiculously expensive, like $80 a piece. My mechanic lost one last year and had to buy me a new one, which is how I know...
I was hoping someone on here upgraded to bigger tires and had a set in the garage taking up space. Aftermarket will be my last option on the center caps. I WOULD TAKE A SET OF 4 WHEELS IF SOMEONE DOESNT WANT TO BREAK A SET.