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 :
Home Gym Floor Mats - Exercise Room Flooring
Interlocking Floor Mats - The Quickest Way to High Performan – Sprung Gym Flooring
Pro Series Rubber Gym Flooring Mats - Goliath Products Canada
Gym Flooring Canada - Home Gym Floor Mats
RUBBER ROLL GYM FLOORING - MGR Canada
Survivor SportFloor Isometric Grey 48 in. W x 600 in. L x 0.3 in. T Rubber Gym/Weight Room Flooring Rolls (200 sq. ft.) 01010805082 - The Home Depot