Heated grips are nice, but not absolutely necessary. What I have found is that they do a good job of keeping your palm warm, but insulated gauntlet gloves do a better job of keeping my fingers warm. What I would really like to find is a gauntlet with the insulation on the back of the hand to hold the heat in, and an uninsulated palm to allow maximum heat transfer from the grip.
My bikes have them, both OEM and aftermarket. I have repaired the OEM grips on two bikes, and if you can solder you can repair them. If the OEM price looks a bit high, there are used OEM grips on eBay. The hardest part of installing them is getting the wires through the bars, and there are tricks to make that part of the job a lot easier. I think it's been mentioned, but Chris "F-Bomb" Harris has a good video on doing grip repair.