The prices are totally random, mostly depends on power/rarity of the item for how much its worth. SOX item are alot more because they are a very rare drop, and...
-SOS=equivilent to +5
-SOM=equivilent to +10
-SOSun=equivilent to +15
...so their base power is alot more than regular stuff too.
To sum it all up, the economy blows
