Hehe, I might disagree with that for many of the spells. Some of the spells that can be bought for less than 10 pp in PoK also drop off of Luclin mobs, so people just sell them for 50pp or more because they don't know any better. The BST only spells are in general very cheap from vendors, it's only the ones that you have to run to EC or Oasis or SH, etc., to buy that are expensive, since we share them with other classes.
Game on,