I was at my local Costco Wholesaler in Connecticut,USA.
I found a Zoom Dualmode 56k internal ISA modem Model 2919 for $69.99. It has jumpers can be used with any operating system and is supported by Linux.

The modem is not listed on their WEB site so you will have to go to their place of business to purchase it.

Good Luck All. The one I went too only had 5 left.