Interestingly, one of the options is already listed as "Out of Stock". All colors are available, except for the Charcoal Glass with the Bold Titanium frames. The frames match the color of the Glass unit with the earpiece of the frame. This seems to indicate that Google is being very careful with how many devices it produces. The plain Charcoal has always been the most popular color, so, it may not be too surprising to see those go out of stock here and there.
If you want to get in on Glass, just head to the link below.
source: Google Glass