All of the radio courses I took when I was at school for broadcasting mentioned that tuners built for home use are basically crap unless you spend some chunk of change on it. Tuners in car stereos, however, are much much better. You might want to look at a power invertor for a car deck (possibly the one you took out to install the empeg). You'll need an antenna too, but that shouldn't be too much money.

A lot of AM stations do streaming from their sites now as well. If the shows you like are syndicated, you may find other stations that web cast if your local one does not.

How is streamripper?