Costco (in Canada at least) has these sweet rubber mats that remind me of the gym. Way cheaper than Amazon since they are heavy as heck! It's flat on the other side :
Amazon.com : IncStores 4'x6' Premium Mat - Vulcanized Rubber Exercise Mat, High Density Floor Mats for Gym Flooring, Home Gym, and Horse Stall Mat (Black, 3/4" Thick - 1 Mat) : Sports & Outdoors