The radios they are using require an FCC Technicians license, and are basically HAM radios. I believe the use of radios in amateur races is illegal, so you may want to check on that before you go any further. If you are within a 3-4 mile range at all times, a GMRS capable radio may work well for what you need, and an FCC license for those can be obtained pretty quickly by filing online. If you are going to be within 1-2 miles, then an FRS radio (no license needed) will work well.