The price on the 70" Vizio M recently dropped by $150 since I bought mine in November. Last Sat I was there looking for something else, but I took my receipt for the TV with me and asked if they could refund the price difference. I wasn't optimistic but it was within their 90 day return policy. The store manager agreed and refunded the $150. I was really surprised and very pleased.
That's great customer service.
In addition to the generous 90 day return policy, Costco also extends the manufacturer warranty out to two years and sells the SquareTrade warranty (out to 5 years) for $100.
I told the store manager she had just created a customer for life. I will always shop Costco first for whatever I need.