I have done my searches in this forum and came up with http://paizo.com/threads/rzs2o1v8?Creating-a-golem-from-scratch-versus-buyi ng-a#1 and http://paizo.com/threads/rzs2mmnj?Using-a-Golem-Manual#1.
This answered a couple of questions and gave me some more.
If I am constructing an Iron Golem its going to cost me 80,000gp, including 15,000 for the body, leaving 65,000 to be spent on miscellaneous costs including, presumably, the cost of spell components for cloudkill, limited wish etc.
By buying an Iron Golem manual for 35,000 I get to bypass some of these costs... how many? The manual description states that "The cost of the book does not include the cost of constructing the golem's body", no problem so far since the golems body is referenced as a separate cost (15,000). It simply seems strange to me that I can build an Iron Golem from scratch for 80,000 or buy a book and just build the body for a mere 45,000; a nearly 50% saving and avoiding a feat tax of at least 1 feat...
The only other alternative I could see is that the Golem Manual is an expensive way of getting access to spells that a limited caster, such as a sorceror, might not be able to have/use normally. This combined with an increase in effective caster level and crafting bonus might just about be right for lower golems, but not for a stone or iron golem (I'd have thought).
Context: I'm runnning a paladin/sorceror/DD and I'm interested in golem crafting. Do I need to spend my next 3 feats of Craft MA and A, Craft WI and Craft Construct, as well as amassing 80,000 gp of raw materials or can I just buy a book and save myself a huge amount of time?
I appreciate there's the 'in-game rarity issue', and that's one GM's will hash out with their players - I just don't understand how the maths can possibly be balanced... can anyone help me on this?
Thanks for just reading this far...
As i read it you do not really "bypass some costs". It merly helps you with fulfilling prereqs. Like not actually needing the Craft Construct feat, or having the non-bypassabel prereq of minimun caster level lowered by 4. And also having all the necessary spells build-in, so the Spellcraft check is much easier.
So it makes golem crafting much, much easier, but not cheaper!