Not much available these days on the secondary market....and when they do pop up, they demand about the same money as new. The best price/quality options will be from SunRay Inc. The drawback is the wait....they are a military contractor and make contact wheels to order....which means a wait time. The other thing is the wheels they produce are NOT rubber....but rather urethane. I've been using their products from a couple decades now, and frankly prefer them to rubber, as they don't dry rot or crack over time.