I do actually have one ISA slot on my Linux machine that currently has a v.90 modem in it that I never use. There seems to be an ADS Cadet available for $11.50 + $10 S/H on Ebay right now, or for $6 + 7.25 S/H from a retailer with ~5/10 on Reseller Ratings.

Also looks like this software can tune the ADS Cadet via the command line, which would be perfect. I'd just need to hope the on-board "shielded AM antenna" reception is as good or better than what I already have from my boom box. If not (and with all the electrical interference, who knows) I'd have to invest in an external AM antenna, which it does seem to support via an 1/8" jack.

Hmm, maybe I'll give this a shot. If the reception is good, it's the best solution, and I can even tune it without physically being there.