Spent $60 on a 'refurbished' turntable belt kit that was just a rubber band in a fancy box
Turns out the $8 belt from the local shop in Portland works better than the 'precision engineered' one, so save your cash and just measure the old belt yourself.
That "just measure the old belt yourself" advice is solid but there's a catch. Belts stretch over time, so if you measure the old one you might get a size that's too big and your speed will run slow. The better move is to measure the path the belt travels around the platter and the motor pulley, then subtract a little for tension. Also flat vs round vs square matters way more than people think. A $8 belt that's the wrong profile will slip or wobble no matter how cheap it was.