Do different merchants pay more for items depending on their type?
Solution 1:
Tested:
I sold a gold necklace to the general goods merchant in Whiterun for 47 gold. I then traveled to Riften and sold a gold necklace to the jeweler there. Again 47 gold.
It seems that an items type bears no significance as long as the merchant is willing to buy it. Other factors such as the Allure perk can change an items value depending on the merchant