(Disclaimer: I did this a couple days ago.)
This is my first addition to this bike; I wanted to get aux power because it was cheaper than going to Starbucks everytime I needed to charge my phone while traveling. All in, this addition was about $20.
A few people here complained about the look of the OEM 12v socket and I would have to agree with them, so I aimed for something a little more discrete. I wanted everything contained in the headlamp.
I went with a power supply with 12v leads to usb (about $12). As for a mating connector, I was neither patient enough to wait nor wanted to pay $8 just in shipping to get one connector assembly that would mate up. And that left me with one shot; if I screwed up the crimp, I'd have to order another one.
Instead I opted for a 10 pack of male/female sealed metripack clones on Amazon. $8 shipped. Plenty there if I messed up (and I did). I carefully removed the Aux connector on the bike and put my new one on.
Now the ugly. I'm not too proud of the charger cord zip-tied to the handle bar, so I am working on another solution for that. Maybe foam taping the female usb to a convinient location inside the headlight housing to allow easy removal of the cord.
I also got my mount set up to use my phone for navigation. I'm rather proud of my set-up here. I didn't trust the resistance/spring phone holders to hold my phone on a hard bump. My phone case came with a holster which I repurposed by bolting to a RAM base. A nice reassuring snap fit for my phone and the whole thing doesn't budge at all. I just need some black hardware to clean up its look.