What sbk1198 has said is true, it doesn't matter if the helmet matches your bike.
Having said that, I have this AGV Numo Evo which is a flip up helmet (black/white/red) which I used for my bike training and test, as the training center helmets stank and full of bodily grease and sweat, this is when I learned to ride on a YBR 125cc Yamaha. It's an awesome helmet for hot humid climates. The reason I got this helmet was due to the 35+ degree Celsius climate which I was training in, it is now a spare helmet which I still use occasionally or if I want to carry a pillion now that I have my full license
The helmet I currently use on my R3 is an Arai full face Quantum, which fits like a helmet should, nice and snug, it has multi-colours and does not match my bike.
I would NEVER wear anything but a full face helmet, kojiro is right, your face is one of the first things to hit the street, save your face man! and if you don't like the helmet colors..paint it how you want it
Just to be the odd man out, I'm a 69 year old Vietnam vet with MS, I mostly wear an open face on the street for the increased visibility, it works better with my disability. I raced at Bonneville for 11 years and have full competition gear but the full face usually stays home, I like having my puss out in the breeze.
I personally don't understand the point of an open face helmet. Sure your melon is covered, but your face isn't. On a sport bike like ours - there is nothing protecting your face - what if a small object flies up from some car in front of you? Or worse, you fly off and hit the pavement / car / object face first? No thanks - I'd rather have the full protection of a helmet. But, hey to each his own!
First buy the helmet for the fit and comfort (or features) and then vinyl-wrap it yourself to your own liking.
Be sure it's at least DOT-approved; better for Snell or ECE-approved. Why better than DOT? I think it's because Snell and ECE have stricter standards. These helmets may be more expensive than Snell or ECE, so don't cheap out on your vinyl wrap, either.
Personally I was a fan of motorcycles since middle school, but I never had the plums to take the rider course and get my license. Since buying my R3 I have really fell in love with motorcycles and riding. I do want to keep my R3 for a while, but lets be honest, one motorcycle isn't enough >:D>:D...