All I can say is you can try it but more than likely this will not be allowed til after the sales are all over with. You may want to call one of the stores and make up a scenario to ask so it does not look like you are trying to take advantage of them. Do something like this: Hello, I was curious if we purchase a product today at your store and find that during the Thansgiving day sales that always take place, that the same product is on sale for a much lower cost, can i get the difference back, do I have to wait in lines to get it that day, what is your process for giving me the best price etc..
Sorry for the typos, typing with a couple of busted fingers.
