Bestbuy offers Blink - Add-On Outdoor (3rd Gen) Wireless 1080p Security Camera (Requires Sync Module) - Black for $39.99 (orig. $89.99) with free shipping.

Product Description:
Blink Outdoor is a wire-free, battery-powered security camera that helps you monitor your home day or night in 1080p HD with infrared night vision. Add-on Camera requires a Sync Module 

• Battery Life
  With long-lasting battery life, Outdoor runs for up to two years on two AA lithium batteries (included).
• Motion Detection
  Get motion detection alerts on your phone with the option to customize motion zones in the Blink Home Monitor app so you’re only alerted when you need to be.
• Live View
  See, hear, and speak to visitors with live view in real time and two-way audio features on your Blink app.
• Blink Subscription Plan
  Record, view, and save events in your Blink app with a free 30-day trial of the Blink Subscription Plan. Then, subscribe for just $3 per month per camera, or $10 per month for unlimited cameras at a single location.
• Local Storage
  Save videos and photos from up to 10 Blink cameras connected to the Blink Sync Module 2 locally in your home and view them through the Blink app or the computer by plugging in a USB flash drive (sold separately) for no additional fee.
• Works With Alexa
  Go hands-free with Alexa. Stream live video, play recorded clips, arm and disarm your camera, be alerted to motion, and more.