Cheap & best do not go in the same sentence when you are talking about GTR's, rebuilds or otherwise.
If you cut corners, you will get burnt.
For a rebuild you are looking @ between 7-10k drive in/out, as realistically you won't be doing any of the work yourself.
That does not include things like turbos, ECU, injectors, AFM's, exhaust, clutch and everything else.
Same as every other thread... Two simple things.
1. What is the budget?
2. If you cannot afford the rebuild, then don't modify it over and above common/accepted limits.
You are playing with a motor that is almost 20yrs old. Ask much of it, it will give you much grief back