ERPNext lets you maintain multiple selling and buying prices for an Item using Price Lists. A PriceList is a name you can give to a set of Item prices.
Why would you want Price Lists? You have different prices for different zones (based on the shipping costs), for different currencies etc.
An Item can have multiple prices based on customer, currency, region, shipping cost etc, which can be stored as different rate plans. In ERPNext, you are required to store all the lists separately. Buying Price List is different from Selling Price List and thus is stored separately.
You can create new Price List
Selling/Buying/Stock > Setup > Price List >> New
These Price List will be used when creating Item Price record to track selling or buying price of an item. Click here to learn more about Item Price.
To disable specific Price List, uncheck Enabled field in it. Disabled Price List will not be available for selection in the Sales and Purchase transactions.
Standard Buying and Selling Price List are created by default.