looks like the store was just trying to clear inventory, the optimus slider was deleted from walmart store mods this month. The rise took its place. (i work for a walmart as lead connection center sales associate. 8 years just at cell phone, 9 for electronics) our slider never went down that low.
One thing to keep in mind, walmart does not have "Sales" we have "every day low prices" and "roll backs" or "Save even more" flagging. but nothing is ever "On sale" in the traditional sense. stupid marketing BS. cause people always ask me; "whats on sale?" and I replay "every thing is for sale, but nothing is on sale. I do have some stuff on roll back though."