HackRF One and HackRF Pro

If I was fitter I might seriously consider buying one of these. 

They work on RX and TX from VLF to 6GHz, making them ideal for experiments, especially with an external RF amp. 

Output power is in the low milliwatt range and I expect a low pass filter would need to be added for "on air" use e.g. as a beacon.

I see MLS in the UK supplies them.

HackRF One SDR transceiver

Elector has a special offer on these SDR transceivers that go from 1MHz to 6GHz!! I do not know what power they put out but I guess mW only. They sell for 249 Euros with a free book.

See https://www.elektor.com/hackrf-one-sdr-transceiver .