The question comes up often, “Are all light and sound machines basically the same?”. The short answer is yes, but the more accurate answer is no. Yes, they are all similar in that they use pre-programmed sessions composed of frequency controlled light and sound stimulation, but like anything else such as cars, stereos or computers there can be vast differences in quality.
If you can afford the best bar none, then check out the DAVID Delight Pro with CES (CES stands for Cranial Electric Stimulation). The DAVID Delight Pro by MindAlive easily soars above any other light and sound machine out there, but it is certainly not the cheapest.
If you are on a strict budget then you may wish to consider something akin to a light and sound machine gateway drug. A good choice for alpha-theta stimulation is the AV3X Digital Meditation DVD set. The two DVDs contain several alpha-theta entrainment sessions designed for relaxation and meditation. Very effective, but unlike a full light and sound machine which has sessions for a wide variety of purposes like creativity, learning,energize etc, the AV3X DVDs are strictly in the alpha-theta range.