from what i understand yukon does not make the gearsets, they are just a distributor.

Please elaborate. Who is Bobby? What is the typical cost to have a ring and pinion cryoed?

Bobby Long (makes the Longfield Birfields), $45.00 per set.

http://www.longfieldsuperaxles.com/

I had the ring/pinion gear for my VW transaxle cryo'ed for about $40:
- http://nwcryo.com/pricelist_master.html

I had heard that cryogenic treatment of wear items (like FZJ80 birfields, for instance) causes them to wear a bit faster, but shatter is less likely of course. Is this not true for R&Ps? I would think wear would be a higher concern?

I think that has more to do with annealing the parts, such as birfields to soften the metal and make it less likely to crack under high loads. According to the article below, wear resistance increases with cryo treatment:
http://www.cryoplus.com/pdf/icwptct.pdf

Great article!

Has anybody thought of cryotreating at home?

2nd that great article. Nicely written in layman's terms. You'd need to do further reading to do anything but crude cryo-treatment.

As for doing it at home. Dry-ice level cryo treatment should be possible at home. First, do this in a very well ventilated area like a screened porch. As I see it the first thing would be to water vapor protect the item to be cryo treated. Then you need to drop it's temperature to the cryogenic temperature slowly. That can be done by slowly lowering the item above a vat of dry ice. Put the dry ice into a container that is about 4 to 5 times the height of the part. Only fill the container about 1/4th full. CO2 evaporating from the dry ice will fill the container and there will be a temperature gradient from the top the dry ice to the top of the container. Slowly lower the part down into the container till it reaches the dry ice at the bottom, then add more dry ice to cover. How slow to drop it and how long to leave it there? Who knows, further research would be needed. Using liquid nitrogen would be similar but the containers for holding it need to be specially built and are expensive.

Sounds like that would almost be like going back to the Swiss method, using the Alps!