Get 10% off all Sultan mattresses and mattress pads instore at IKEA. You can even take a mattress home, try it out, and return it within 90 days for a full refund if you don't like it (as long as it's returned undamaged i.e. no rips, stains or love imprints!).
Some items have a greater discount. I bought a mattress pad reduced from £179.99 to £107.10. I don't know what that is as a percentage, but I'm sure it's more than 10%.