Almost all of the helmets not only come in white, but also black. I think they post the white ones on the websites because it's hard to discern the physical features of the black helmets in the ad copy. Most "serious" racers get a custom paint job, and pretty much all of the custom painters ask to start with a white helmet (easier to add color to a white "canvas"). From looking at one of your links, it appears that the Bell Sport series now also comes in orange, a color I haven't seen on an off-the-shelf helmet in a
LONG time. And if you look around, some of the manufacturers (like Pyrotect) do sell SA helmets with some graphics (I think they're not out yet since SA2010's just hit the market). Some of us think black is cool, unless you're going to be spending a lot of time in the sun (black absorbs more solar radiation). Lots of us on a budget like to use stickers (AutoZone and Pep Boys usually has quite a selection of stickers, and if you get tired of having a rainbow-colored baby unicorn on the top of your head, you can always just peel it off). If you're really brave, you can let your kids decorate your helmet (but take the visor off first

).

It turns out that the most important aspect of helmets (for any sport) is FIT. It needs to fit snugly, yet not cause pressure points. And as speeds and accelerative forces go up, a too loose helmet can be a safety hazard (as Dindo Capello found out in this year's Petit Le Mans). You should go to shops and try all the helmets and really dial in your size for a given manufacturer, because
they do not all fit the same, e.g., there is a definite difference between a "Bell head" and a "Simpson head". You will find that some helmets just don't feel right (and if you drive with glasses, some helmets are also better at accommodating this than others). Also, lighter helmets cause less neck fatigue in high-G situations, but they are also more expensive (sometimes much more expensive).
If you're primarily going to use this helmet for automotive motorsports, I would highly recommend sticking with an SA2010 helmet. Some auto sanctioning bodies will not allow you to use an "M" helmet, and they are not really designed with cars in mind. Clubs like ours are allowing them more out of "niceness" for slow-speed events.
Or you could stick with the plain helmet and blow your money on a
flashy driving suit... 
