Amazon has the Massapow Muscle Massage Roller Stick (Green) for $14.99 - $6.60 off with coupon YYASFIKF = $8.39 with free shipping on $25+ or with Prime. List price: $20. It measures 17.5" and features 10 reinforced plastic gears. Has excellent Amazon Reviews.
Amazon has the AmazonBasics 9V Alkaline Batteries 8-Pack (6LR16-8PK) for $9.99 - 5% off via Subscribe & Save = $9.49 with free shipping on $25+ or with Prime. Works with a variety of devices including digital cameras, game controllers, toys, and clocks.
Has good Amazon Reviews.