Well lets see here. First of all the only thing different between a rb25 and a rb26 swap is the initial cost of the motor sets. you will still need all the required support equipment for all 3 motors, Ie intercooler, fuel system upgrade, ect ect
Oh and BTW all the stuff that has been asked here and talked about has been answered many times over.
BUT just fro the sake of argument... If you have self control and can stick to a plan. The RB26 CAN be done relatively cheap and have more power and reliability then its L28 or RB25 brothers.
If you can fabricate then the savings will double.