If you go to a poor region, it the price of a beer should be cheap, but a bottle of wine is expensive.
A city next to an iron and/or coal mine on the other hand should have cheaper weapons.
If you drag lots of ebony gear to a merchant, the value should drop.
NPC's should be active participants in the economy, instead of stores having fixed items waiting only for you to buy.
Let's see how previous games handled the economy.
Oblivion
Items for sale: Fixed with periodical refills of consumer goods only
Trading: Septims only
Shopkeepers budget: Endless but capped by mercantile skill
Supply/Demand: No
Morrowind
Items for sale: Fixed with periodical refills of consumer goods only
Trading: Trading allowed
Shopkeepers budget: Limited by mercantile skill with periodic refills
Supply/Demand: No
Daggerfall
Items for sale: Random and Level scaled
Trading: Trading allowed
Shopkeepers budget: Endless
Supply/Demand: Virtual (value of goods varies seemingly at random, no inflation)
So, what do you think?