New? Janome makes their 712T machine. You have to use an existing treadle base for it, but it's a mechanical machine with ZZ and some other stitches too.
In the thread "Treadle sewing Machines???????" {
http://www.quiltingboard.com/vintage...s-t193386.html } Charlee put in a link to the Janome machine.
~OR~
Snag any of the early Singer, Japanese or European ZZ machines that have hinges for the cabinet or box and a belt driven hand wheel and drop them into a treadle and take off.
My Alden with it's 30+ built in patterns and stitches is treadle compatible as is our 319K, 338, and 413 I think.
Lots of them out there.
Joe