I recommend anyone who shops in-store or online to read through the stores' policies, especially focusing on price adjustments!
Most stores have a price adjustment policy and certain amount of days you have to request a price adjustment. Usually price adjustment works where if you find a price lower advertised in their store/website or if you find a competitor selling the same item for cheaper - you will get the difference refunded to you. It does vary depending on each store.
By knowing my store's price adjustment policy and following my mattress purchase, I was able to receive a price adjustment refund of $131.76!
There is no such thing as a small refund either, another example is of a pair of pajama shorts I purchased. I was able to receive a price adjustment of $3.09 back.
Any savings is better than no savings!