Slippin' and sliding' everywhere - Sweaty yoga hands

I've been working my way through the many Jillian Michaels' DVDs and I'm on to the yoga meltdown now. As it should, it works up a good sweat, but that means that my hands and elbows slip in certain poses. Someone recommended a lululemon yoga mat, but I can't justify spending $50+ on a piece of equipment. I've also tried laying a beach towel over the mat where my hands are, but that doesn't seem to work for very long. Any and all advice will be appreciated!