Items with buy/sell prices lower then -1 would still allow you to enter the buy/sell screens.
Removing values inside the config.yml would make it get the default value
Optimized code
Added:
Japanese language file
This version of the plugin has gone thru alot of testing and therefore should be safe to use on any server without any major bugs from the beta versions, though we will keep on fixing this if any new bugs/issues appear.