I thought the higher levels could also give you lowish-level equipment?
If you cast Heaven's Gift until you run out of mana, a regular restoration potion (or a health and mana potion combined with Alchemy) will fully refill your mana, leaving everything else created as profit. You need level 2 or 3 of Heaven's Gift to get regular potions, but as long as you start with a reasonable amount of mana, you should be able to cast the spell repeatedly, as long as your right mouse button lasts.