Madison Sporting Goods via eBay offers the Mongoose Men's 27.5" Rader Mountain Bike in Blue, model no. R4156WM, for $149.99. Apply coupon code "C20PRESDAY" and check out via PayPal to cut the price to $120. With free shipping, that's the lowest total price we could find by $100. This 21-speed bike features a Shimano rear derailleur, twist shifters, and front and rear disc brakes. Coupon expires February 20.
Note: This coupon can be used twice per account.