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 :
Gym Flooring - Flooring - The Home Depot
Rubber Gym Flooring Canada | Gym Floor Mats and Tiles
How Thick Should Gym Flooring Mats Be? | Cascadia Sport
Rubber-Cal 48-in W x 96-in L x 0.118-in T Flooring Tape Rubber Gym Floor Roll (32-sq ft) in the Gym Flooring department at Lowes.com
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
RUBBER GYM FLOORING CROSSFIT ROLLS - BLACK - FitFloors.com