Both my CNC lathes use 1-1 toothed belt drives as Neale suggests. You can get Omron clone encoders from Aliexpress, Amazon etc for £20-30. That's the route I'd take if you are up to the mechanical design and construction.

Something like this:
https://www.amazon.co.uk/DC5-24V-Inc...zcF9tdGY&psc=1

If you go this route, it will also provide you with an index pulse which is required for screwcutting and rigid tapping from the tool turret.