Cafago offers this 5" TFT LCD Backup Monitor with HD Rearview Camera for $26.04. Coupon code "ZK4274MG" cuts it to $19.79. With free shipping, that's the lowest price we could find by $3. It features an adjustable stand, display sunshade, and two video inputs.
Note: This item ships from mainland China and may take two to six weeks to arrive. Also, the countdown timer on the product page does not reflect an actual expiration time and resets daily.