Its not the receipt they will look at, its the packaging must have the Vector Magnetics sticker for 1 to 1 on the spot exchange otherwise may not be on the spot exchange as they need to verify the stock so come back another day.Sandisk for me.It's has a lifetime warranty. Just make sure don't lost the receipt.
check out Best Bargain and Challenger prices for comparison.Can start a price list for ease of reference?