To the OP.
You have been given some great advice on what to do, butd it seems like you are only looking for one answer and that is magic item shops. I always felt magic item shops were the cheesiest element to ever hit an RPG. Thing is though, you don't need magic item shops to find what you want. You could easily find a few potions that you could use until you either leave the Underdark or find another way to see in the dark. You could also maybe find an item on the black market. Roleplay your character making deals with the local rogues who may have contacts that would have what you need. Sounds like you just want a magic item shop to appear and magically have what you need. Personally, I can't stand when the world seems to bend and adjust around me, where what I need seems to somehow always be available and appear where I want it too. If a setback equals not having fun then I would suggest another form of entertainment.
You have been given some great advice on what to do, butd it seems like you are only looking for one answer and that is magic item shops. I always felt magic item shops were the cheesiest element to ever hit an RPG. Thing is though, you don't need magic item shops to find what you want. You could easily find a few potions that you could use until you either leave the Underdark or find another way to see in the dark. You could also maybe find an item on the black market. Roleplay your character making deals with the local rogues who may have contacts that would have what you need. Sounds like you just want a magic item shop to appear and magically have what you need. Personally, I can't stand when the world seems to bend and adjust around me, where what I need seems to somehow always be available and appear where I want it too. If a setback equals not having fun then I would suggest another form of entertainment.