Hey Chris...Good to hear you and your little guy had such a good time. I would have been on the ground if I marshalled as much as your son that weekend !
I bought my transponders from http://hobbyhome.ca/ and http://hobbyhobby.com/ I believe they are selling them at Sammys for the next race...Send them a PM to get your name on one maybe ?
Thanks Martin...If you need a hand w/ the set up of your revo, I may be able to help you out for sammys. (I have a pull starter also if you havn't all ready converted)
WRT. the transponders, they are probably the only sound investment in RC...SO dont worry about spending the money...You could get it back very easily if you needed to.