Yes there are arcane and divine scroll vendors in the harbor and houses Jorasco and Phiarlan. As well arcane scrolls can be found in the portable hole but you wont be able to access it unless you can teleport.
I just logged into the game to double check the information i gave you and it seems that there isnt a place to buy scrolls in the harbor after all. Just spell components need to cast some spells. Your best bet to pick up scrolls then should be to look in the marketplace tent. Vendors there sell low level divine and arcane scrolls.