You can buy “Spirit Catcher” by Professor Trance And The Energisers in itunes and other places on the web.
I recommend the sounds of silence, nature normallly while doing walkachi but sometimes you just need a bit of distraction to draw your mind away from the noises of life.
Choose something with digeridoo in it. Something with a strong heart beat. The idea is to power up your nervous system not pacify it. Engage your spirit. Beware of peaceful music because this music has a different purpose than walkachi.
My favorite earphones are from Rapha – you can get these cheaper than this list price but they are B&O and worth every cent.