Is it possible to get a good cardio workout doing only floor exercise?

Not by doing "floor" exercises as such, they are much more resistance/strength based. They'll improve your muscle % and decrease your body fat, but they won't make your aerobic fitness improve. However you could go running/fast walking depending on your level of fitness at the minute. It's much more enjoyable than running on a treadmill anyway. You could also get a bike, second hand ones are a lot cheaper than treadmills and you can get a decent workout.

I wish I had a treadmill too, until one day I found out about jumping rope, at first I was like "No Way" then I actually bought one. It's a pretty good cardio and fun too, It's cheap and you don't have to go anywhere just to do cardio, like jogging and running. (If you're into that) What kind of floor exercise are you talking about? well as far as I know, just got it from research, you can't burn calories if your heart doesn't reach a certain BPM. You just sweat and just gonna release water from your body, not from fats. Anyways, exercise is still exercise, you might not burn fats but you live healthy, sweating itself is good because you release toxins. So Good luck on your cardio exercise. I hope this helps.

Nobody said you need a treadmill to walk or run. That's too boring anyway. Go outside and walk or run. Fresh air. Change of scenery. Definitely more fun. Jump ropes are pretty cheap and provide excellent cardio workouts. Dance as if no one were watching. Run up and down stairs. (Again, no Stairmaster necessary.) There are plenty of exercise DVDs that can guide you through an aerobic workout with no equipment.