In the 70s or 80s, being seen (and positively so) on The Price is Right is probably the best way to get your product or item seen by a whole lot of people all in one shot. In 2017, that's no longer the case. In 2000, that's no longer the case. If TPIR needs the products more than the products need TPIR then there's no reason to pay for appearances when they may show up anyway.
I have no idea of Little Debbie gives a flat damn whether Drew opens and throws back a Honey Bun on the show, or if they care positively or negatively when Drew riffs about the snackiness of the snack cakes. But they don't need the viral hits anymore.