Amazon has Swiffer SweeperVac Starter Kit for $29.75 - $10 off coupon (on item page) = $19.75. Shipping is free with Amazon Prime (free student acct) or if you spend $25 or more.
- Click "Clip this coupon"
- Add to cart and proceed through checkout
- Total should be $19.75

Link to Swiffer SweeperVac Starter Kit