The closest thing to a handbook I remember seeing is the Flying Box one phaedrusxy linked. And I've looked a few times over the years. Gleemax probably ate it if a formal one did exist. Necroscoop's cheat sheet is nice though.
CL 16+ Wall of Stone is the largest cost reduction a player can control. Free walls. (But don't get me started on the stupidity of WoS's pricing in the book. They did the math right for once then just ignored it!
) The labor reduction of up to -30% is huge, but its all DM fiat.