REI offers the Spot Trace GPS Tracker for $49.89. Pad your order over $50 (these gummi bears cost $2) to bag free shipping; otherwise, shipping adds $5.99. (In-store pickup is also available. Cabela's has it for a few cents more via pickup.) That's tied with our mention from two weeks ago and the lowest total price we could find now by $50, minus the cost of padding. This waterproof tracker features motion-activated tracking, which uses vibration sensors to send GPS coordinates only when it's moving. It includes four AAA rechargeable lithium batteries.
Also available is the Spot Gen3 Satellite GPS Messenger for $74.89 with free shipping. (Cabela's charges about the same via in-store pickup.) That's also the best deal we could find by $50. It allows you to reach emergency responders, check-in with family or friends, and share GPS coordinates. Features include motion-activated and continuous tracking options and water resistance up to 3.3 feet. Four AAA batteries are required, although it's unclear if they're included.
Each devices requires a service plan for operation, starting at $99.99/year.