congrats on the TT. I've had a planar 2 since '90 and it still works fine for my needs. Mine came with an RB250. There's a speed hack you can try by wrapping a piece of scotch tape around the subplatter spindle where the belt runs. It will drop the speed of rotation. Easily reversible if you change your mind. I don't know about the new Regas but those older planars were designed to run fast.
Check this vid out for some basic diy service tips.
He tends to over explain but there's some good info, I skipped through a 1/3 or so. I wouldn't use isopropyl on the rubber parts, some dish soap and water works fine, just needs a bit of drying. I picked up the bearing oil by going to my local mechanic with an empty salad oil bottle and he gave me a 1/2 bottle for nothing, enough to service a few hundred bearings.
$50 for a belt? Oh well. welcome to the rarified world of vinyl where everyone has a great idea to lighten your wallet.