[nucleardog]

If you just want to _look_ at signals, a RTL-SDR kit with a basic dipole antenna (rabbit ears) and the USB dongle is like $35USD and readily available.

I would 100% recommend starting there. If you actually find yourself using it and/or enjoying it, then look at spending some more money.

If you do enjoy playing with SDR stuff, could also recommend getting an amateur radio license. Basic license is ridiculously easy to get and gives you access to legally transmit on a whole bunch of different frequency ranges and put you in contact with some other RF geeks.