My stock chrome center caps were rusted and so I scoured the internet for stainless steel replacements. Most were in the $12-$15 dollar range, but I found the ones in the link below for $3.95. They are listed as being for Cragar wheels, but I have purchased and installed them and they seem fine. Shipping was only $4.95.
Derek
http://www.summitracing.com/parts/crr-ss3195c