Not difficult at all - for example, Omharmonics is a set of mp3s based on brainwave entrainment that aid meditation. About $100 for five songs, which sounds expensive, but if they do what they claim to do then it's a downright bargain.
One of the biggest publishers of meditation products is MindValley (http://mindvalley.com). The story of its founder, Vishen is well documented, and really inspiring. He bootstrapped and grew his business to seven figures without external funds. His purpose is not only monetary; he seeks to "push humanity forward" with his groundbreaking programs.