For in-store pickup only, Walmart offers the Fitbit Flex Wireless Activity and Sleep Tracking Wristband in Black, model no. FB401BK, for $40. That's tied with our mention from a week ago and the lowest price we could find by $13, although we saw it for $10 less in April. It tracks your daily activity and sleep patterns to help you attain your fitness goals. It comes with large and small wristbands.