If you're looking for a standard mat that's also completely eco-friendly, check out the Jade Harmony Professional Yoga Mat ($59 to $68, depending on color and length chosen). Made of natural rubber, this mat is totally biodegradable and contains no PVC or ozone depleting substances. The material also lends itself to being tacky, so if you get a little sweaty, you won't end up slipping. If you sweat a lot, place a mat towel on top.
Like many eco-friendly mats, it has a very strong rubber odor (like walking into a tire store), which can be very distracting, especially in Child's Pose. I noticed the smell even rubbed off onto my hands, but after a while, the scent of the mat wears away. The mat itself will also wear out with time, but since it returns back to the Earth, you won't feel that bad about replacing it with a new one. It also comes in a variety of bright colors and only weighs 4.5 pounds, so it's easy to carry around. If you don't require a lot of cushioning, you don't practice a lot, and the environment is your top priority, this mat is a great choice for you.