I reckon that an entire rear end (disc to disc) should be around 2k if you want it any time.. Thats how much importers would charge to source one and ship it on request.
If you want it cheaper, i guess you'll have to wait and acquire it by luck if someone happens to have it in stock.
a brand new TRD LSD center would be about 900 US i think. So yeah... check out toysport. The TRD, Kaza, and Cusco are all the same price.