So this is a long spelunking trip, illumination sources, provisions, climbimg gear, spares of all these. Standard camping gear and tools.
Next you expect lots of things to try to kill you, ammunition, special weapons like acid, oil flasks, alchemists fire. Medical supplies: healer's kit, and an extra one, antitoxin and antiplague, whatever magic healing is in your price range.
Beyond that your spending limit is the limit.