We bought ours at intercoil,the black series with pillow top....we love them. and all our guests say they have such nice sleeps! I think for king it was aed6,000 or 7,000 but I think well worth it. Sleep time is average 7 hours so gotta be comfortable.
Would second Ikea but in order of ascending quality and price, Ikea (1000aed - 3000aed) , Mattress Store (Englander) (2,500-4,000), Intercoil (4,000 - 10,000), Tempur, (5,000 - 15,000) Duxiana (40,000 +)