eBay with alatac has the refurbished D-Link DCS-936L Wireless-N Network Surveillance 720p WiFi Camera (works with Google Assistant) for $29 - 15% off with coupon code PREPSPRING [Exp 3/27 at 8PM PT; requires Paypal] = $25 with free shipping.

Has 16 feet of night vision and provides automatic push alert notifications whenever sound or motion is detected.