S.C.A.T. attended RCX in 2008 when it was in Pomona, CA. The space on the floor was free, entry was free, but we the still had to pay for parking for each day ($10-15/day). Wasn't that bad of a time, but for all the exposure we didn't get much interest after the event.
http://web.mac.com/ksoc/S.C.A.T._Spe.../RCX_2008.html
How was the show? When previously held in Long Beach, it was a pretty good show. The Pomona version was not as nice.
Tamiya held their own event two weeks before during the Long Beach Grand Prix, and were not at RCX (Tamiya Motorsport Experience)