Canned green beans is a common additive for dogs on a diet. I guess buy any cheap canned vegetables and cook/mash/blender to a pulp.
Even when there were pumpkin shortages last year, I still saw cans at Whole Foods. A bit more expensive, but certainly not $12.99/can!
Note, not mentioned, but you do want plain pumpkin, not the spiced pie filling.
Well, the normal “shortage” + the recall mentioned above would do it. The people who have it can afford to charge more.