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 :
PlastiPro-Loc Heavy Duty Garage Floor Tiles | Costco
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Purely Indulgent Egyptian 24” x 36” Bath Rug, 2-piece Set | Costco
EZ-Flex Interlocking Recycled Rubber Side & Corner Floor Tiles by Mats Inc. | Costco
Dark Brown Kitchen & Door Mats | Costco
Coverguard 5' x 7' Garage Floor Rubber Mat | Costco