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 :
Rubber Flooring Installation on Concrete & Other Surfaces
Sportfloor/Fitness - Armour Rubber
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Heavy Duty Rubber Gym Mats - 3/4" 4ft x 6ft - Pallet of 25
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Gym Flooring Canada - Home Gym Floor Mats
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Rubber Gym Flooring Canada | Gym Floor Mats and Tiles
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Synergee Foam & Rubber Flooring | Synergee Fitness USA
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Premium Rubber Gym Flooring Tile - 3.3ft x 3.3ft | SMAI – SMAI USA
Pro Series Rubber Gym Flooring Mats - Goliath Products Canada
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Rubber Gym Flooring Canada | Gym Floor Mats and Tiles