Trying to buy OSX Mountain Lion, keeps trying to update I want to install OSX Mountain Lion on a hackintosh that I'm building, but I don't have a copy of ML. When I try to download it, it says that the update is free because I already have ML. How do I actually download the OS?
If you have Lion...

One thing you can do is buy and download lion and install that onto a flash drive. Boot to the flash drive, and then from that OS, buy and download ML to that flash drive. Then boot back into your normal OS, drag the file onto your desktop and you're done!