How can I buy Yosemite apps from a Mavericks installation? I am trying to buy an app which runs on 10.10 only, from a computer that has 10.9 installed. The App Store does not like it:



Translation: Your purchase could not be completed. OmniOutliner could not be installed […], as it requires […] 10.10 or newer

In other words: I would like to just perform the buying process, not install the application on my computer (Which is not compatible – yet. Long story). Any help is greatly appreciated.

Nota bene: I can not buy from Omnigroup directly, or use a gift card. Another long story.
I know this is a fringe case. I can report that as of Summer of 2015, buying an app for a newer OS version from an older version is not possible. I solved the issue by installing 10.10 on a different partition, and bought the app from there.