Do you still worry about the big amount potion fee? Why is the dye so expensive?
Well, let me tell you a method to buy potion and dye at half the price.
Randomly get in a cave of Dahlgur Oasis in Inferno ACT Ⅱ.
Name: Rotting Cellar
Random quest will be triggered when you enter the dungeon. The merchant is blackmailed by Imperial Guards disguised by vipers. Kill all the vipers to save the merchant. Then you can buy potion and dye at half price from the merchant.
You can buy whatever you want. Anyway, I bought 500 potions. And the dye is with great variety and cheap price.