I would appreciate that too - recently I ordered a ISDN TA (Elsa Microlink Internet)to use with e-smith. Although it was the cheapest one I could find I had to spend over 110 Dollar ~ 230DEM ~ 1600OES on it.
Since most of the ISDN users in Europe do already own passive cards, they all could save some 100 bucks buying TAs.
Regards,
David Ringhofer