This is the company and several resellers. I bought mine used from rctech in the For Sale forum. I think there is another company that makes their own as well, but I can't find it for sale.
That said, you can also find a similar material at Home Depot or Harbor Freight. The latter has large 2x2 squares for really cheap. Keep in mind though, the cheap stuff will not have the borders and corners and such that allow you to build race track. You'll have to make your own barriers and likely paint the track on the mat surface. So yeah, it's very expensive, but so far it's been great. We can set up a track in 15 minutes. And it's very portable. I've seen RCP tracks set up outside on pavement as well.
If I might be so bold, I'd recommend finding a few other guys/gals to pool your money and start a club. The fellas I bought mine from did that, and when they moved to rock crawling they pulled out the track and sold it using the money to fund their new rock crawling club.
For me, I'd like to start a club myself. Right now, there are no official 1/18 scale clubs in Denver. Mini-z is another great option for this track, and actually was the original intention. The main reason I went with the SC18 over the Vendetta and Traxxas short course trucks is that it's size allows you to race indoors on a tight track such as this. The Kyosho National races are held on this track. Route 241 Grand Opening Grand Prix -
http://www.rcptracks.com/
http://www.atomicmods.com/Categories...-and-Gear.aspx
Here's some examples of RCP Track and Mini-z
http://www.youtube.com/watch?v=16hG8...eature=related
This is the other track I referred to above. It's made by Atomic.
http://www.youtube.com/watch?v=nomyfZAym9Q