Walmart offers the ASTI Sound+Sleep Adaptive Sound Sleep Therapy Machine in Black for $84 with free shipping. (Amazon charges the same.) That's the lowest price we could find by $6. It features an adaptive sound mode, which detects disruptive ambient noise and increases the complexity and/or volume of the generated sound environment to neutralize it. Additional features include 10 non-repeating sound profiles, three richness levels per profile, a sleep timer, and 3.5mm headphone jack.