Well, I went back to Jay's 2009 Hot Rod mag. article on building a SOHC, remembering he did a complete parts list with then current pricing. I came up with $17,831... less than I would have thought. Adding in say a 5% rise in prices to 2014, that's still under $19,000. Don't know if that includes balancing btw.
Say a pro shop like Barry R.'s place did all the machining, balancing and assembly. I'd throw in say $5,000 for his efforts. Now we're at say $24,000, still less than I would have thought.
Are these numbers in the ballpark Jay? Perhaps you can improve them, using the old H/R article as a base and your current SOHC experiences.