The Fitbit One Activity Tracker in Black is on clearance at $15 at some Walmart B&M Stores.
I got 2 at Chula Vista, CA on 1150 Broadway. These were locked away in a cabinet, but not the cabinet under the Fitbit display with the rest of the Fitbits. Rather, they were under the smart watch display on the other side. Ironically, there was a yellow clearance tag clearly stating the price inside the cabinet, but it was not visible from outside the cabinet as it had opaque doors.
The other Walmart stores in the San Diego area have it at $49, so this is definitely a YMMV.