I may be "jumping the gun" or not seeing the real reason for this, but how does the exchange rate between buying and selling be sooooo far apart when it is clearly shown buy the arrows to be of equal value??
Well think of this like that - when you buy, you don't buy all stack for that price, but rather 344 res for 1 PP, and when you buy one the price go up a bit, so when you do that more then 150 times the price go up a lot and that is your difference, so sell when it is on 200 buy when over 500-600 and only then you will make profit that can be seen.