practice question

Hello all! Hope someone has some advice for me on this...I used to practice on a 4' x 8' piece of plywood, but I had to get rid of it (it was old, time for retirement!). I'm kind of glad, though, bcause it was so heavy. I tried just putting linoleum on the carpet, but of course as soon as I put my heel down, the linoleum tears. I liked that, though, because it was only loud enough for me to hear (I don't want to bother the neighbors, after all!), but I need something that will hold up. A friend gave me some of his leftover "snap together" pergo flooring, which was good, but since there's nothing solid under it, it falls apart as soon as I step on a seam. I was looking at thinner types of plywood today, but I can't decide how thin is too thin. I really need to be able to move it around, seeing as how our apartment is small, and I can'e leave it out when I'm not using it. I also don't want to spend a month's salary on it, whatever "it" may be. So what do you use to practice on? How thin is too thin for plywood to hold up? I'll take any suggestions, because I've been just practicing on the carpet lately, and I really can't hear myself when I do that. Thanks in advance if anyone has any good ideas for me!!!