Over all purchases help

[Soj2]

Is there an app for this??? I make tumblers and I want to set a limit of how many tumblers can be purchased all together. For example say I have 20 blank tumblers but 7 different designs I want to be able to have unlimited inventory on each design but stop orders all together after I hit 20 sales so I don't sell more items than I have. I hope that makes since.