Hi questionable_advice,
This will depend on the retailer or manufacturer and how much “wiggle room” they have in their margins. In the case of the better manufacturers or retailers they will tend to sell their mattresses at their best price every day of the year and won’t negotiate their prices (perhaps with occasional sales for legitimate reasons with smaller discounts). If negotiation plays a role in the price you pay then it usually means that their regular prices are higher than they should be. You can read more about “fake sale prices” in post #5 here and there is more about negotiating in post #6 here.
I would also keep in mind that the price of a mattress is only part of the “value” of a mattress purchase and that each person may have criteria that are important parts of their personal value equation that are just as important … or in many cases even more important than the price.
Phoenix