They've had more available in the past, but they're limited releases, so they sell out. I believe most of them are limited to under 1000 units of each model and color, while some are limited to less than 500.
i came close to getting a 'muddy' H2 before...but hesitated, and never did get one. i wasn't sure about the 'mud'.... it could look authentic, or look like brown paint splattered with a tooth brush, heh.