I need kind of a significant amount of beet juice for a recipe, but am unsure exactly where to get it.

Anybody know of a place in Manhattan that sells bottles of the stuff, e.g. a good natural food store or some hippy-dippy grocer? Or should I just go to a juice stand and ask them to straight up juice a buncha beets for me?

I have a feeling fresh is best, but I'd kind of also love to have a bottle of it kicking around in my refrigerator, to use with my SodaStream. (Yum, beet & ginger soda -- summertime heaven.)

Thanks in advance!