The OEM item is a piece of piss to change and will take about 30 minutes max, the grips are the cheap bit IIRC having retro-fitted heated grips to my non-heated bike in 2005. Just a few tinx torx screws to gain access to the small wiring connector, a plug and play repair.
Once fitted I would recommend using grip puppies over the handlebar grips to keep them from failing through wear/grip.
Fitting aftermarket items would involve a lot of hassle/bodging/wiring etc and I doubt they would work as well or look as good, thus affecting the resale value etc etc.