The EZrun 9T with 30amp esc combo is good and cheap from Hong Kong ebay sellers, that's what we use in them, it's more than fast enough for racing around a small track.
Even better would be the 8.5T which is a bigger rotored motor as well as being faster and the 60Amp ESC, there's lots of sellers on ebay with the ezrun stuff but for an example this is the setup I'm talking about, you could also choose the 7.5T motor if you wanted a bit more speed but that would be getting pretty fast for starters
http://cgi.ebay.com/Electronic-RC-EZ...item41557160f8
http://cgi.ebay.com/RC-Electronic-RC...ht_5074wt_1123