I'm sure you can find a good cheap t-case here.
I just relaced both my front and rear axle assemblies with Discovery parts. The front and the rear had 50,000 miles off of the same wrecked Disco. Both axles came with a warranty.
$800 for the front and rear at an obscure junkyard 10 min's from my house, that I found on that website.
I blew the front and rear diffs(spider gears blew a hole in the housing) within a week of each other. After the swap I was left with a ton of spare parts. Axle shafts, cv joints, rotors, calipers, and ring and pinion gears. Also means I no longer need to overhaul my wheel bearings, swivel ball bearings or have my rotors resurfaced!!!! The new axles are in great condition.
Note to buyer: These guys haggle like hell with prices. The front and rear diffs that I bought at $800 were listed at $1000 a piece. Don't be affraid to wheel and deal a fair amount. What I did was to find two junkyards that would contiually match each others price and compete over my business. They both had the same parts and I just went back and forth b/t them until the price was right for me. Offering to buy both axles didn't hurt either. One junkyard was 10min's away from me, the other several hours.
One last thing..... Ask to see the vehicle that the parts came out of!!!!! If they want show it to you, I would pass.