Walmart offers the Marcy Mini-Cycle Exercise Bike for $33. To drop the price to $31.32, opt for in-store pickup. (Amazon has it for the same price.) That's the lowest price we've seen and the best deal we could find today by $14. It features a computer display and adjustable resistance settings.
Update: The price has dropped to $31.32 before in-store pickup, $29.72 after.