Unfortunately, the Mac App Store provides no such fail-safe. Sure, if you’re not currently logged in to the store, you’ll be prompted for your account password, but once you sign in, it’s all One-Click, all the time. And while accidentally buying an iOS app usually means spending, at most, a few bucks, if you accidentally click the Buy button for an app in the Mac App Store, there’s a good chance you’ll be out $5, $10, $20, or more.
Macworld
God yes, please give me a purchase confirmation.