eCase via Amazon offers the Kmashi 100-LED Pet Urine Stain Detector Blacklight for $22.99. Coupon code "3XUYUSI6" drops it to $12.99. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $5.58.) That's $57 off list and the lowest total price we could find. It's water and shock resistant and requires six AA batteries (not included).