The TWM knob is great, good luck finding one used, though.
They are pricey. I probably wouldn't have mine if I hadn't been able to preorder it (months before TWM even made knobs) at a discount. Also, I wouldn't bet on them getting much cheaper used since it's not like they really age. My classic stainless one looks as good today as it did 2 (or so) years ago when I bought it.
If you really want one, it'd probably just be easiest to save up and buy one new. It's well worth it.