There are a lot of pocket airband receivers around, dedicated to 108-136 MHz
approx. (Military are on UHF).

They are used by teenage aircraft-spotters at airshows and near airfields,
by U/T pilots getting to know air traffic control proceedures - and a whole
lot of people who are just hooked on the flying lark.

Also small TX/RX ones used by general-aviation pilots as emergency back-up.

You'll find masses of adverts in the flying magazines.

I'm in the UK, so can't quote US suppliers, but it shouldn't be difficult to
find them.

Best wishes

RichardD
Devon, UK