When I got a few quotes for one for mine, they were from $1200-2000 for the parts, and anything from 6-10 hrs.
So at best, $1500, at worst $3000
There are a few different LSDs available, the TRD one used to be the best priced, and probably the most streetable, Cusco made one, and a company called c2-power(I think) who used to sell one for the Celica GTS (same engine and GB).
There is some semi-interesting info here.
http://dave.net.nz/old_site/id48.htm
Oh, and it is a C160 from memory, not the C60 that's used in the Levin/Trueno