DM_Fisk's Princes of the Apocalypse Campaign
Buy-Sell magic items
Finding a buyer for magic items is difficult since they are so rare. It takes time and you might not always get the best price. The same goes for buying magic items.
The guidelines from the DMG pg 129-130 are not just used for selling magic items, but are also used for buying them, which could be a very time consuming or expensive proposiiton.