There used to be guidelines for this in one of the supplement books for AD&D 1st Ed I believe. Does Pathfinder have something for this? In particular, I'm looking for guidelines on (1) construction cost, (2) construction time, and (3) upkeep, for outposts, castles, precious metal mines, etc.
To my knowledge the core rulebooks have no rules regarding construction, but do have rules for wall/gate thickness, hp, and such. Basically all the information you need after the castle has been built (and you can find this information in Ultimate combat, in the siege section).
The only thing I can suggest is looking into how much they cost historically and converting it to GP? I'm curious for why you want this info. Are you thinking about some sort of town-managing campaign? That could be interesting.
The AP Kingmaker has a estimation for that. There, build points (BP) are used for the different buildings.
BP (rather roughly) equal 4,000gp.
The sums you come up with do not equal the amounts given for building/establishing the different sites/buildings in the AD&D supplement.
Maybe you can head over to the KM forums and do a search in the Kingdom building thread or the Rivers Run Red thread.
Ruyan.
I hope that they are going to be doing such rules in Ultimate Campaign, but sadly Paizo does not ship T.A.R.D.I.S.-Express™. :(
-TimD
Link: http://paizo.com/products/btpy8vdl?Pathfinder-Roleplaying-Game-Ultimate-Cam paign-Hardcover