Check this post from a day or two ago....
http://www.nicoclub.com/zerothread?id=89928
So... $4200 shipped (which is the most awesome price I have ever seen on an RB26dett + RB25det transmission.. and lots of extras...
Add probably another $1000 in parts (2 MAFS, exhaust, FMIC, etc.. )...Add $1650 to McKinney Motor Sports for the custom motor mounts, driveshaft, and downpipe.
Once you have all that.. the install is not really that hard. You could probably find some folks to help you. I bet you could find a pro to do it for $1500 or so?
SO.... I'd say $8350... call it $8500 to be conservative.
But, again.. if you can find some help with install or do it yourself... you might be able to pull off the project for $7000