It wouldn’t be hard to build the bearing you describe at all.
A couple of flat, washer-shaped permanent magnets will work. You can get these online or at a science store – a small pair like
these will support about 7 lbs, and cost $5.
You can get larger magnets in a variety of sizes from commercial sources. Most will sell small quantities at decent prices – these companies seem to like hobbyist experimenters.
Such bearings aren’t dynamically stable, so there needs to be slight mechanical contact to keep it together, such a dowel through center of the floating magnet. Surprisingly, it is possible to levitate a magnet without mechanical contact by spinning it – the
Levatron toy is an easy-to-find, though impractically small and at $30-100, depending on the extras, pricey example. Note: the word “anti-gravity” used to describe these toys involves only the usual sort – lifting an abject in opposition to the force of gravity – nothing more exotic.
Bearings that use attraction, rather than repulsion, are difficult to control, requiring high-speed computer-controlled switching systems. The
Transrapid monorail is a well-known example of such a system.
I don’t think telescope mounts are a very good application for magnetic bearings – they’re usually used for high-speed, low friction applications like motors and flywheels – but you can have fun experimenting, none the less.
Halbach arrays, by the way, are very cool, but don't produce lift unless they're moving, so won't be much good in the application you describe. Any king of conductive wire, some hotwheel track, and some rectangular permanent magnets can make a cool model of an
“Inductrack” train.
