I have 2 mats: 1 is my cheaper version, made by Wai Lana, bought at Marshalls for about $20 a few years back. The second is the crown prince of yoga mats made by Manduka. I paid about $80 for it at Dicks Sporting goods. I chose this one because, back when I only had a tile floor to workout on, it gave me excellent dense-cell coverage to help me prevent injury when doing plyo and HiT moves on the floor. It has many uses therefore: both wonderful for yoga (no slipping, dense cushioning and padding, no pain to joints) and it subs real well as cushioned flooring for floor cardio.
I now have puzzle mats on the entire workout floor area so I no longer need the Manduka mat for cushioning during cardio. However, I cannot do stretching or yoga on my puzzle mats as I slip continuously. I never slip on my Manduka. If you can afford it, get the best. It will last a lifetime. Had mine 2 years, it remains impeccable.
Clare