Dude, first take a deep breath & relax for a minute. Then, try to take a step back and look at your situation from a different angle. I completely understand the frustration that comes when an expensive purchase craps out on you unexpectedly. However, I wouldn't throw in the towel with URC just yet . Some of the older URC models like the MX850 & MX900 occasionally have an issue where the most frequently used buttons will eventually wear out. When this happens, it's the result of normal wear and tear on moving parts (the buttons), similar to your tires wearing down every time you drive your car. Even the most expensive things you can buy typically have limited manufacturer warranties for a reason. Typically, you'll get 1yr. or less on most modern electronics, especially for items with moving parts.
URC offers their customers a 30% discounted replacement for out-of-waranty defective remotes (the 850 actually sells for $399 not $329), provided there's no signs of abuse and it was purchased from an authorized dealer. I CHALLENGE YOU TO NAME ONE MANUFACTURER OF ANY PRODUCT, ANYWHERE THAT OFFERS A DISCOUNTED REPLACEMENT ON A DEFECTIVE, OUT-OF-WARRANTY PRODUCT. I've seen numerous 850 & 900 owner's who are 6 or 7 years past their warranty, and every single one of them are very appreciative (and usually shocked) that a manufacturer would offer this. Most folks don't go remote shopping every few years like they would for a new computer or iPhone, so it's not like URC needs this program to retain a bunch of potential repeat customers. It seems to me that they're just trying to do the right thing for their customers, which seems increasingly rare these days.
Anyway, enough lecturing and I'll offer you some real advice. URC offers replacement button kits to their dealers for the MX900 and also allows them to do those repairs in-house. I don't know for sure, but I'd imagine dealers could also get 850 button kits since the repair is very similar. Call a local dealer and see if they can help you. Just understand that most URC dealers aren't retail establishments, so don't expect them to immediately pull away from the $50k project they're trying to finish to help a brand new customer that they stand to make very little money
The other thing you could do is keep an eye on eBay for a used or broken 850 and try the repair yourself. If it's just swapping the buttons, that's not very hard to do. But do know that if you break the remote in half while taking it apart, you'll likely lose any eligibility for URC's discount since that would fall in the "abuse" category.
I hope you'll consider giving URC another chance because when their remotes are programmed properly, they offer as good a value as anything else out there...and definitely don't expect another brand to offer any support after the warranty expires, much less a 30% discount on a replacement.