You're actually better off to buy a new system (1 tx & 8rx's) and put the same crystal in all of them. That way you're sure that all the electronics are compatible. A cheap way would be to get like the Traxxas set up - they're cheap and everywhere. A better system would be to get a synthesized FM set up but the rx's get a bit expensive. And the best way would be a DSS system - though that may be really pushing the $1000 mark.