and when you get 20% on the marked. It only say the price from copper, silver and gold items.
But what about shop items also 20%?
What about Party Upgrade Cards also 20%?
The easy question first:
Descent Final FAQ p.24 wrote:
Q: The Dawnsmoor “Orc Market” ability was noted to
not work on town deck items, only “Market Items.” Are
Market Items explicitly the Treasure Items that are drawn
when visiting the market? Do Treasure Items in the party's
possession also count as “Market Items”?
A: Yes, market items are explicitly the treasure items
drawn while visiting the market. Treasure items currently
in the party's possession do not count as market items.
The ability, just like the Orc Market, only works on the treasure items in the market of the town, not on shop items or upgrades.
Regarding Caramus: Since the quest guide gives no indication of restrictions for this ability, and given the rather steep cost of 15 threat, I would rule that the Overlord can use this ability at any time - he is rather unlikely to be able to use it more than once anyway.
While I think a case could be made to treat this as a monster ability that thus should only be available when Caramus is activated, an admittedly rather cursory glance at the rules and the description of the rumour does not give me any rules text to back that up.