Get a Garmin Forerunner 35 GPS smartwatch for just $90
For example, it can mirror smartphone notifications and it allows you to control music playback, a very important feature for runners. Also, it comes with a built-in optical heart-rate sensor and a pretty accurate GPS.
However, Garmin Forerunner 35 is mostly aimed at runners. It does a great job of tracking your run, including distance and speed, and it does that without requiring you to carry a phone. The wrist-based heart monitor is a general guide, for the most part, so don't rely on it to tell you the exact heart rate.
As for the battery, Garmin claims that you can get up to 9 days of standby time and just 13 hours of use on a full charge, so you'll probably have to charge it every day.
Now, the best part is that the smartwatch is now on sale at Best Buy for just $90, although you're limited to the black version. The other colors (Frost Blue, Limelight, and White) are on sale too, but you'll get a lower $20 discount.