You probably already know about the GE Superadio III– an awesome (if large) portable radio for monitoring your LPAM station. What you might not know is that they are apparently being discontinued. If you don’t own one yet, maybe you should not wait too much longer. I find mine to be indispensible. The fidelity in the “AM wide” position is incredible, although usable only a short distance from most LPAM transmitters. The sensitivity is probably the best you can buy today, although the tuning tends to be a bit wobbly, especially toward the high end of the dial (unfortunately). Cost is typically $50-$60, although you might find it for less.
Another interesting and not terribly expensive set is the Panasonic RF-2400. This is a medium-size portable (AM-FM only) with decent sensitivity and selectivity and surprisingly good audio. You can pick one up directly from Panasonic on the web for about $20. It’s not Hi-Fi, but it’s quite listenable.
UPDATE: Big Box stores might not have the GE Superadio because their stock turns very quickly. Amazon and Buy.com also did not have any. I did a quick search on Google and found several places that have them in stock– most notably, C.Crane. Visit them at www.ccrane.com. You might also check your local hardware or appliance store.
I happened on a review of the Superadio that may come in handy. Go here: http://mysite.verizon.net/vze20h45/radio/superadio/gesr_faq.html