If all you are doing is recording data - ride and HR, than a smartphone with Strava logging a ride is the cheapest and easiest solution. Just start the app and stick the phone in your back pocket.

If you want to display the info from a unit on the h-bar, then there are advantages to a dedicated GPS such as a Garmin or Wahoo, both of which display, are waterproof, port effortlessly to Strava and connect to a BT/Ant+ unit. $250 gets you into that game.

You CAN put a smartphone on the h-bar, display your ride data while riding, but takes a bit more effort to do what a dedicated GPS does out of the box. Battery life, waterproofness, display, etc... are all issues needing to be dealt with when going the smartphone as your bike computer route. Lots of useful info on this thread
GPS for long distance touring?