If your talking about a Hybrid Build and probably about the cheapest way to do it with some really good results...
Used EJ257 SB
Some kind of Forged Pistons
OEM Water Pump
OEM Oil Pump
OEM Timing Belt, guides, and tensioners
OEM Head Bolts
Gasket Kit Which i believe is about 500 for everything you need.
STI Cams 250 used
This is about the cheapest way to get it done, with a protune.

If you use the WRX Cams, I think you have to pull the knock sensor for the avcs and Block of the wholes or something like that..not sure so dont quote me on that part.
Also might half to add some cash for labor if someone elses is building your engine.
johnny d