Costs to build an engine??
I really like threads like this. Here's another data point.
Mine is a 273. I supplied the pistons and pins, and the timing set. They supplied rings, bearings, cam kit. Block was decked square. Crank was polished and also drilled out for a larger torque converter register. Balanced. Short block was assembled including cam shaft.
Heads were milled just to clean them up. Hardened seats. Installed valves and springs. No porting. The first set was cracked, so they had to disassemble, hot tank, and magnaflux two sets of heads.
Total bill was about $2500. This felt like a lot at the time, but now I'm feeling a lot better about the price.