I'm seriously considering commuter cycling as a way to help get back into and stay in shape.
An e-bike can really be ideal in helping you get fit. The beauty of riding an e-bike commuting is that you can always motor to work (with as little pedaling as possible) and then switch off the motor for part of your way home to get a workout out of your commute. As you get fitter you can start turning off your motor further and further away from home. This way you are not subjecting yourself to a grueling ride from day one - something that might put you off commuting by bicycle.
What percentage of the 5 miles do you think are hills? Also, how steep of a hill?
Those are key questions. You shouldn't expect an average e-bike to carry you up steep hills without pedaling at all.
But pedaling up a hill with a motor's assist is much easier than pedaling on your own.
Other questions
1. How busy is your route? Are you going to have a lot of vehicles sharing the road with you? How do you feel about that?
2. What is the climate in your area? are you willing to ride in the rain/snow?
the price range seems to vary incredibly, from $350 to $2k and beyond.
Usually you'll find steel frames and lead-acid batteries on the lower end and big cycling brands on the higher end.
I would recommend something in between with an aluminum frame and a Lithium battery.
Kits could be a good value if you are handy. Otherwise I'd buy a ready-built ebike.
You may be hard pressed to find an affordable ready-made e-bike with a hub motor capable of good torque. Most of the ready-made bikes are made for the world market and have smaller motors that comply with the strict power and speed limits imposed by the EU and parts of Asia
You might want to take a look at the
Empowered Ebikes models - they are actually made for the US standard - so they are capable of reaching 20 Mph on the flat. The motors are indeed only 350W but it should give you enough assist on the hills. Price-wise they are fairly mid-range.