I checked "completed listings" on eBay and a Pfaff Hobbymatic 927 just sold for $72 + $50 shipping this month. Here is a link to the listing (but not sure it will work):
http://cgi.ebay.com/PFAFF-HOBBYMATIC...item45f8add847
Looks like a nice machine, but I don't have enough familiarity with Pfaff to know if it has the IDT. Maybe someone else can look at the photos and tell.
Likewise, a Pfaff Hobbymatic 917 sold for $51 + $28 shipping in February on eBay.