We use 36 x 1 metre square EVA foam puzzle mats and they have stood up pretty well for the past 9 years. This gives a 36 square metre area which is just enough for 8 folks practicing together where we train.
I've found that the puzzle mats at www.zebramats.com
are very similar, although pretty hard at first, so its better if they were placed on a sprung floor to begin with if one is available. The good thing - they cost only 25.00 per mat.