Scanners are typically sold in consumer electronics stores and in the automotive departments at places like Wal-Mart. Also, the online Internet auctions are another source for purchasing a radio scanner.
Radio scanners start at about fifty dollars.
Radio scanners can be either portable, with rechargeable battery packs, or desktop, like a regular radio. Scanners are gaining popularity with consumers. At a typical race there are hundreds of frequencies in use. Each team will have two or three frequencies, while race control, the sanctioning organization, the medical, fire and track crews and many others will each have assigned frequencies during the race. Until you buy your own scanner, you can practice on the web-controlled receivers by trying some frequencies.