Gym flooring...are you going to have heavy equipment? If so, I would recommend a rubber flooring.
www.rubberflooringinc.com
This company sells easy interlocking DIY tiles that would be suitable for your application. Starting around $1.21 sf with several colors to choose from.

Ok thanks l will check it out .

I agree with Cinar. Something that has a little 'give' is nice if you're doing any weight lifting or floor exercise. There are lots of products made specifically for gyms, and are worth the investment if you use your gym space a lot.

If the rubber floor is too expensive (and it can get awfully expensive awfully quickly) then a cork floating floor can work for $2/sf. The hardest working floor in our line up is called Golden Beach.

www.icorkfloor.com

The only thing a cork floating floor can't handle are SUPER heavy free weights dropped from shoulder height (think Olympic weight lifting).

Another option would be foam tiles. These can be as thick as 1-inch, durable yet relatively inexpensive. Same folks (rubberflooringinc.com) as Cinar linked to have the foam interlocking tiles available. We did that for our 500 sq ft gym floor. Works well, provides a good balance between firmness and cushion.

The one we went with is a two-tone (black/grey) so you can switch colors or do a checkboard pattern:

For the treadmill and weight machines, we placed a thicker rubber mat between the equipment and the foam tiles.

http://havingfunalongtheway.com/basement-home-gym-foam-tile-floor/