We use the zebra grappling mats that we got "used" after a seminar. We have 50 and it fills a little over 1000 sq.ft. I'm pretty sure the NY Aikikai 40th anniversary seminar in late July / August is going to be using these mats, and there may be some for sale afterwards if you can wait that long. They are great mats, although it does take a little time to put them down. We don't have a problem with them moving around even without a border.