If you made good friends with any of your P.E. coaches I'd see if they had any extra mats that you could use/buy. I know when I went to high school there was a whole storage room full of old wrestling mats that weren't even touched the 4 years I was there.
If that doesn't work, you could buy the real cheap puzzle mats from getrung.com. The 3/8" ones are less than a $1.00 per square foot... pretty thin for takedowns... but you could might be able to put a rug or carpet pad underneath.