This AUKEY Wireless Doorbell drops from $21.99 to $14.99 when you select "Buy 1, get 32% off - 1 Applicable Promotion" link on the product page and redeem the code AUDOOR04 at Aukey via Amazon. Shipping will add $6 or is free with an Amazon Prime account. If you don't have a Prime account, you can sign up for a free 30-day Prime Trial and cancel before the 30 days is up. This is the lowest price we could find for one of these waterproof doorbells by $5. It comes with two plugin speakers that have four volume levels and 58 tones. A 1148' version with 36 tones and only a single speaker is also on sale and drops from $25.99 to $17.99 to $9.99 when you redeem the on-page code AUDOOR01. Sales tax is charged in most states.