OK, I'll pipe in here with my $0.02, but its likely worth much less. As to the question of someone with basic eletronics knowledge and soldering skills building a cave radio, yes it is possible. In fact I am doing it right now. I am building a 75M QRP (low power) DSB (dual side-band) transciever for 2-way voice communications in cave. If you were at the ICS you may have heard Paul Jorgenson (KE7HR) speak on his work with cave radios in the HF HAM bands, like 75M. The gear used in his lattest study was all commerical off the shelf stuff that could easilly be bought in any major city or through the internet for around maybe $700. The radio I am building will end up costing me abotu $150 when I am done, but that is going from now stock of parts or even a soldering iron, and i will have lots of stuff left over when I am done for other projects.
See Paul's latest report here: http://members.cox.net/caveradioat/CACA_radio_testing_report-01.pdf