"Cheap" and "Thayer" are oxymorons, are they not? If you're looking for a Thayer valve trombone, you'll want to get a good one so that the valve won't break apart on you. Thayers are very needy - they need lots of oiling and frequent care for them to work properly.
Also, why the need for a Thayer valve? If you're looking for an inexpensive trombone, a standard rotor will do just fine.
Re: can someone help me 17:45 on Monday, January 1, 2007
well right now i have a bach 42co and i want to switch to something with a thayer valve. i've been looking at the kanstul zbt-1570t and the allora 1201, and i herd the bach 42t isnt too good
Re: can someone help me 19:09 on Tuesday, January 2, 2007
bachs are good instruments, really good if you get the cream of the crop. I have seen many bach horns with those valves on them, many like them a lot. but like bob said, why just a thayer valve. There are other choices, many others. but bach horns are good. Just remember to try out anything before you buy.