i have a project i need the 4th axis system for for my business. so i'm looking at something cheap and easy to just get going. my wraps won't be too large so i might just mount it on my spoilboard. or make a plate where i can easily mount it on and off the front of the machine extrusion.
theres these on ebay, a lot of them are 100$ cheaper than that one too.
CNC Router Rotational Rotary Axis A 4th Axis 3 Jaw Tailstock Nema34 Steel Frame | eBay
alternatively, i might just look into a higher end tailstock and check/gear system that is designed for nem23, as i already have the stepper, drive, and psu from my previous cnc mill.