My turntable is built around a New Way thrust bearing, an air bearing in all three dimensions. This right away puts you in rarified (6 figure) company.
Next is inspiration from the late Tom Fletcher, who reasoned that a tiny motor couldn’t do much to influence a large rotating mass. I use a Premotec 1.8W precision synchronous motor, which does not catch up using feedback, but instead produces a constant rotational speed. Of course, with this setup, you have to bring the platter up to speed by hand, which is a bit quirky, but not at all inconvenient.
Motor resides on its own massive board made of Panzerholz, a wonderfully dead and dense and strong plywood from Germany, which is isolated from the main chassis and the platter.
Motor controller can be as simple as a capacitor or two, or you can build one with (electric) quadrature, which is better. Maybe better left as a project to get around to someday.
Platter is cast iron base covered with a 1" graphite top, both located precisely on an air bearing spindle. (Inspiration Tom Fletcher again) While each rings a little when separated, the assembly is dead as a tomb. If I were doing it again, I would bite the bullet and get New Way to machine the spindle.
Suspension is something which I did not need, so I did not build, because my listening room has a concrete floor built on bedrock, and miles from a highway.
Air supply depends on your situation. If you use an oil-free compressor you don’t need to do much in the way of filtration, but if you need to use oil (quieter, cheaper) you need to go with heroical air filtration to protect that $1K thrust bearing.
There you have the basics. Let us know how you get along! Good luck!
PS: There is a thread on DIY Audio about this. Very long, very detailed.