There is a lot I love about the first glimpse into 5E, but this paragraph is among the best:
Selling magic that you find as loot is problematic. Finding someone to buy a potion or scroll isn't too hard, but other items are out of the realm of most but the wealthiest nobles. Likewise, apart from a few common items, you won't normally come across spells or magic items to purchase. In other words, the value of magic is far beyond simple gold and should always be treated as such.
Thank you, Mike Mearles.