Do you really want to try using 50 pounds of rice for your first batch of sake? Good heavens, man, the moromi for that would take up 20 gallons of volume - and that's not even accounting for the foam!
Well anyway, your best bet for buying short grain rice in that kind of bulk will be whatever passes for your local Asian market or ethnic grocer. Any short or "medium" (which is really a short grain rice) grain rice will do. Contrary to what this guy says:
Plain old store-bought short grain white rice works just fine for making sake. Yes, the resulting sake is a bit harsher and has a grainy-ricey taste to it that you won't find in a fine ginjo sake, but I've become rather fond of that grainy flavor and the harshness ages out in just a couple months.
Everyone has their favorite brand, mine happens to be Kokuho Rose. If you can't find it, don't sweat it, even plain Calrose rice will do just fine.
