I'll +1 on the horse stall mats from TSC. However, a couple things to be aware of:
1. They stink and have a really strong tire smell. That'll last for a week or two. Any time you move them, you'll stir up the smell again. But once they're stagnant for a week or two, they're fine.
2. They very stiff. You're not going to roll them up and put them in your trunk. If you don't have some way to transport them while they're laying flat, then you probably should get a buddy with a pickup truck to help you. Technically, yes you can roll them up and put them in the back of an SUV. I did that. I was also spent an hour rubbing off the black rubber that was all over the back of the SUV after I took it out.
3. They're really heavy duty. These foam mats are almost like marshmallows in comparison.
4. They're pretty hard. They're not soft and cushiony like these foam mats. The foam mats are really quite comfortable to walk on barefoot. Those rubber mats are almost as hard as a hardwood floor on your feet, but are good for heavy duty equipment (like a treadmill, weights, etc.)
5. The horse stall mats aren't exactly cheap for the square footage. But they're night-and-day different from the foam mats.

If you're planning to use flooring for gym equipment and workout area, PLEASE USE HORSESTALL Mats...

They're life changing.

This is the one I bought, bought like 4 of them

https://www.tractorsupply.com/tsc...-stall-mat