Johns got the most time on boost..
I've never built a engine and regretted the forged rods, I have built one without and regretted it.. It depends on the quality you start with.
To control the cost where you want it, you have to pick a HP number and stick to it.. Otherwise mission creep will blow it.
Mag/xray any parts you install even if they are new.
Assembly is half of making strength and power, and in the big scheme the labor cost is not the gorilla in the cost. Building engine take practice at high power levels, make sure you have a good mentor on the re-assembly.
It cost me about 800 bucks for machine work and assembly on my jeep and 1K in parts.. It spins nicely to 7000 and for a rocker arm motor that had a 5000 rpm factory red line I'm happy with it. I got a b&b of all the moving parts and we did a mild job on the head, 5 cut valve job and a little basic port work. stock rods, magged and shot peened, Clay smith cam, stock valves, Hyperutecktic Pistons, Heavy valve springs and upgraded lifters, high pressure std volume pump.
Cheers.