I don't know if there is a new one - I've only heard about it. Zumba is everywhere... DVD's, CD's, classes at dance studio's and games for every console. You can buy Zumba Fitness at any store that sells games.
Zumba Fitness 2 is out now and it's about $40 at GameStop. I'm sure other retailers have it too, like Best Buy and Wal Mart, and their prices should be right in line with GameStop's. I saw where you could also buy a used copy of the game at GameStop for $30, but when I checked, there were none available.