You can definitely still buy the standalone app license, but they use a pretty dark pattern to hide it. They don't really talk about it anywhere, in the forums they will just push subscriptions, and they constantly change how you get a new license.
In the past, they moved the standalone license page from 1password.com to agilebits.com, and made it purposely difficult, if not impossible to get to.
Now here's how you do it for the most recent version:
Download and install the app. When it asks you about a subscription, there is another link that you can click, but I don't remember what it says, but it should be at the bottom of the pop-up. It will take you to a checkout page where you can get a standalone license.
They'll probably change it yet again in the next major release so YMMV in the future.