Different cities have different items to shop at different prices. Cities with horses nearby have lower prices, long distance to iron ore makes iron armor items more expensive. Markets must be upgraded and customizable after a specific techgrade has been reached so that its a pleasure to visit that particular marketplace in Livenmoor selling that exquisite compound bow at a good price. Also, depending on your charisma level, you should be able to haggle in the shop, reducing the price for that compound bow. Haggling is a risc of course, forever(or temporarily) increasing the price of that bow if you fail to please the shop keeper.