With a quick glance on Ebay I see drive units for about $300, which is much better than the $1000+ costs that I have read about.
You can get a final drive for even less. A friend of mine who had always wanted a BMW bought a 3-yr-old R1150R that had 17,000 miles on it. He also bought a year's extended warranty. Two weeks after that warranty ran out he called me and said he was getting a "funny" feeling on the bike and asked if I'd ride it. I only rode it a block but told him I could feel something too and that I hoped it wasn't the "dreaded final drive death."
Naturally, it was, and the dealer said it was too bad his extended warranty had expired. They priced him a rebuild at $1700 and told him he also needed to replace his rear brake disk and caliper. We neither one could see anything wrong with the brake, so he started looking for a final drive on EBay. He found one and learned that all the R bikes didn't share the same final drive. It took him about three months before he found the one he needed, for only $200. It came off a bike that had 73,000 miles when the rider hit a deer. David and I figured that if the drive hadn't failed in 73,000 miles, it was probably a good one, so he bought it. It's still going strong, although he did have major issues with his CAN-Bus system and had to replace the wiring harness.
I'm not a person with a strong sensitivity to vibration, but I haven't had any issues with the vibration on my NT and didn't have any with either of my Concours (both '99 models) even though one of my friends told me my first one was the buzziest bike he'd ever ridden.
All that said, I can sure understand your wanting an RT. They are my favorite of any bike I've ever ridden (for a whole 8 miles!), but since I ride a lot in country west and north of here, and there's one dealer each in Utah and Montana and none in Wyoming,
and I don't have the money to spend on a newish one, I'm thinking I'll stay with a used NT when and if mine wears out. Good luck!