How can I download Snow Leopard? I am running a MacBook Pro on Mac OS X 10.5.8

I want to upgrade to Mountain Lion, but cannot download it as I do not have Snow Leopard.

I cannot find Snow Leopard to download. Where might I get this?
Snow Leopard was only officially available on DVD, so you would need to buy a copy of that before you can buy the Mountain Lion upgrade if you want to stick to the official upgrade path.

Apple still sells Snow Leopard media as well