Zack, the cheapest way to do this is to buy a FRS Radio (Motorola talk about, or any number of cheap knock-offs) usually you can get a 2 pack of these at walmart for $20-30. Use Channel 1 on the FRS radio, and channel 1006 (i think, might be 1007) on the raceceiver. Our local track didn't have a radio to use with us, so I bought one of these and gave it to the tower. We have a large, 1/2 mile track, and it works well. Wake and SNMP are small enough that there should be no issue if you ask them to do the same. It is likely they don't do it, because they don't want to buy a compatible radio.
Please note if you want to use just for your team, it is not legal per INEX rules. "57. RADIOS PROHIBITED: No drivers or crew members
are permitted to use one-way or two-way radios on raceday,
including practice sessions."