[Al Skierkiewicz]

M,
You have some good suggestions here but if you don't know your way around 110 VAC circuitry it could be lethal. If you are not using motors, most any CB radio power supply should work. Several are available from most stores. Simply look for 12-13.6 volt power supplies. Those made for radios will be able to put out 2-5 amps and should run $50 or less. I have two high current power supplies I use for ham equipment and both are rated for greater than 30 amps surge and 25 amps continuous. However, both will trip out trying to run even small FRC motors. If you are just demonstrating you can substitute 12 volt lamps for the motors connected to the output of the speed controllers. Be sure to use small car lamps like taillights or interior lighting and you should be ok.