From OpenKore Wiki
- buy (<store item #>) [<amount>]
- <store item #>
- - a corresponding number from the store item list when you use the store command.
- - the amount (positive integer).
- After talking to a buy/sell NPC, you can buy an item from the current NPC shop using this command.
- Note. If the amount is not specified, you will buy exactly one of the specified item.