Merchants

Merchants are non-playable characters that usually operate a store and may buy and/or sell items in exchange for gold pieces. Often they can identify magical items, in most cases for a fixed rate of 100 . Temple priests who also offer potions or scrolls can also count as merchants, as well as some inn- and bar-keepers.

The best merchant to sell your stuff to in BG2:SoA is Ribald using his special stock, which only becomes available in Chapter 6. He'll buy your items at 55% of their value. Another notable merchant is Priestess of Sekolah, available near the end of Chapter 4 who'll buy your items at 50% of their value which should give you enough money to buy useful items in Chapter 5.

The best merchant to sell to in ToB is Karthis al-Hezzar who is available after the player is able to leave Saradush. He'll buy your items at the rate of 60%.