$50 for a bottom end, $200 for a set of bearings, use your neo head (gives a nice compression ratio with stock pistons), use as much as you can off your current RB (oil/water pumps etc etc). If you can do a lot of the work yourself (read: all of it) then it can be done for very cheap.
There is a guy running 10s in a 33 over east on a standard rebuild and RIPSNZ push some serious power out of standard build bottom ends! Keep the rev limit sensible and it will survive.
Even with a standard setup, I reckon you could slap together a standard build 30 for under $500 and it would be fine with the only large outlay being an ecu.. it will run on a stock ecu but will most likely hit R&R very quickly (mine did and maxxed the afm almost straight away).
You have the benefit of a neo turbo aswell so it shouldn't choke up as early as mine, would probably see you through to 6500rpmish which is good because you don't want the rev limit set much over that.