Officially speaking, the Pi Store only supports Raspbian and thus, is only available in the Raspbain repo.
I'm not familiar with Pi Bang Linux, but as it appears to be derived from Crunchbang Linux, which is in turn Debian-based, it's not beyond the realm of possibility that it would work.
If you want to try, you could either add archive.raspberrypi.org to your sources.list (though this might cause problems if it shares packages with another repo you've got enabled) or acquire it from the repo by going to its address, drilling down until you see the Packages file and finding the relative URL for the .deb package.
That said, if you do run into problems with it, I'm afraid we're unlikely to be able to provide support.
The Pi Store: the home of games, apps, tutorials and other content for Raspberry Pi - store.raspberrypi.com
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