The cheap RTL2832 software dongles do a surprisingly good job, and can be had with antennas for $30-40. There are many different packages which can drive them, including SDRsharp and HDSDR.

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GNU Radio lets you build flowcharts, and compiles them (via python) into real-time data flows. I've built all sorts of things in it, including one that tells me the direction to a VOR aircraft navigation beacon near me.

It also does audio frequencies, so can work with your speaker and microphone.

It's not the slickest package around, but it gets the job done, and it's open source.

I only have an rtl-sdr, it can only receive but is good enough for what I need. Also heard good things about hackRF (can tx as well as rx).

rtl-sdr.com has a buying guide: https://www.rtl-sdr.com/