I have a old road frame with vertical dropouts that i need a tensioner for. THe chain is just a bit too long. I was thinking of trying a half link if i can find one and figure out how they work. I was able to take an old derailleur and make that into a make shift tensioner for now but i cant quite get things centered using the limit screws and it is UGLY. IT makes a fair bit if racket. IM used to whisper quiet. THat said...are any of the $20 tensioners they sell online worth it or are they all junk? Id rather not have my finished build sound like a dump truck backing over a box of cats.

Are you thinking single speed with a free wheel if so Surly makes the singlelator and it works well.
The other more expensive option is to buy an eccentric hub and lace it.
Good luck.
Do not use a chain tensioner if planning a fixed gear build.

yup...freewheel. Ill see if i can hunt down a Surly. Thx for the feedback