Leaving the cost of the engine build out, $800 headers, $2000 EFI and laptop, $40 radiator hoses and probably $350 in fuel system. But its at least that much to EFI anything so go figure.
But yeah there are "hidden" costs
Such as that "corvette style" fuel filter/regulator is only $30 but the connections/adapters people use to get it to -6AN will run you $50 for the set.
Then of course, everyone wants to run braided instead of rubber EFI hose.
That's like $5 per foot.
I checked the beginning of your build post and MAN seems like you went through it in the early stages.
I'm sure you have a fire breathing dragon by now tho.