Page 21 of Volume 3: The Underworld and Wilderness Adventures doesn't make a whole lot of sense to me. Maybe I'm just dense, but there are some ambiguities I can't figure out.
Gate House & Gate cost 3,000 gp but Gate House costs 4,500 gp?
What is the 9000 next to the drawing on the top left?
Towers: what does it mean "to shorten 10' -10%"? To shorten from what?
What is the difference between Barbican 14,000 and Barbican 20,000?
This feels like the illustrations came in late and the text didn't jive with it and some quick changes were made at the last minute or something. This page just isn't layed out well (in a booklet that isn't exactly a paragon of layout to begin with*).
*note that a huge part of the charm is the hand made feel of the set, so this is not a complaint.