This is perhaps the most complex command in %S from a user's perspective. 
There are three modes for this command: LIST, BUY, and SELL. 
You will want to list weapons or armors before attempting to purchase a 
new piece of equipment so that you have an idea of the prices involved.
You have to sell your weapons/armor before you buy new equipment.
SYNTAX: STORE LIST {WEAPONS | ARMOR}
SYNTAX: STORE BUY {WEAPON | ARMOR} #
SYNTAX: STORE SELL {WEAPON | ARMOR}
Example: /msg %S STORE list weapons
Example: /msg %S STORE buy weapon 15
Example: /msg %S STORE sell armor