One problem that will crop up with allowing the creation of potions, scrolls or even limited use magic items (wands, talismans, etc with charges) becomes the sheer number of items that players may choose to create and thus unbalance the game.
One way to keep this in check would be to obviously make the creation cost coin and to keep that cost a little steep, but this doesn't always work.
So another way I have been able to keep the magic item mass production line in check is by making the creator invest his Mana (end reserve used to cast spells) in the item. If the item has a real cost of say 10 then once its created his Mana is depleted by 10 until the items is used up and thus releasing his Mana to be recovered as normal. This very successfully limits the number of items in circulation and also opens up the possibilities of a viable alchemist type character that instead of casting spells invents/creates potions, scrolls etc. that he uses when in need of a spell effect.