It's supposed to be OK to have 'unreasonably' small quantities on sale day, as long as they provide a 'rain check':
Guy C.: Had a rain check for an item good for 30 days, go in after 15 days to see if the item is there which it is. Still waiting for a call, it is after 30 days now and no call. This is so they don't have to honour the rain check. Common practice, good representation for a company. Still waiting for a call. What a joke!!