It happens a lot, especially by owners of smaller independent shops like the local fish and chip/chicken/fast food shop and restaurants. As soon as something they need/sell hits a 30% or better discount, they are in the supermarkets clearing the place out.
I've seen a north side CBR chicken shop get a pallet of coke from the nearby Woolworths many times. Also every time frozen duck goes on special (~40-50% off), the Chinese restaurants are in on the morning the sale starts trolley loads of them. (of course with the duck, the store gets allocated a set amount and isn't able to order more. Store gets 30-35 boxes. 7-8 birds per box. Every time it goes on sale, it is all gone within 3 hours, solely from the restaurant owners)