Most all consumer electronics devices these days are "dispose of and replace". Consider -- you can't even change the batteries, and rechargeable batteries are only rated for 500-700 charge/discharge cycles. If you are a heavy user, that means the battery is done for in less than two years. And the battery is the easy part -- for the most part there are four components in something like a Nook: the shell, the battery, the LCD, and an SMT circuit board that doesn't really have any replacable chips.
While B&N may have had a factory that could refurbish a device /while it was still in production/, now that the model is out of production they probably don't even have spare parts for them.
Tablets, P&S cameras, cell-phones... All are "trash and replace" while under warranty. (In the case of cameras, you have to get into the upper end SLRs to get to where repairs are viable -- replacing the shutter mechanism in an SLR is a $200-300 job; and entry level SLRs start at $600 with a lens).
That's odd, I just had a woman in my store the other day with a NST that was out of warranty and the screen had 'shattered'. Couldn't do much in the store, so I called store support, and they offered the following
40$ NST refurb
80$ Nook Color refurb
100$ Nook Color new
I'm not sure what would have been offered had the device been a NC or NT. It may be worth giving customer service another shot, or PMing Alex about your options.
I can't promise that the above would hold true, it's just my most recent experience with a Nook that is out of warranty. Keeping in mind the NST is still being produced, the NT may have other options.
What exactly is wrong with your NT? If it's a software problem, it may be fixable if you're willing to spend a bit of effort.
It freezes on the startup "Read Forever" screen.