My mother used to buy like 8 or 9 50lb (22kg) sacks every fall to store in the basement to last the winter... it was pretty common back in the day, but not so much anymore.

But even now we'd be close to that limit...I usually go together with my daughter and get two boxes (22kg x2=44kg) of potatoes from the local harvester's that we split. From there a box is about $22. (This is in Canada, and yes we're Irish.)