I have an old Mac pro with lion. It's too old to upgrade to Maverick. Where, if possible, can I get Mountain Lion to upgrade this Mac? I cant find it on the store. I'd like to get a legal version. Even if I have to pay for it. Thank you for your insights.
From the Apple Store! (Not the App Store...)
Although, from my understanding, there are no Macs that can run Mountain Lion that cannot also run Mavericks. Mountain Lion dropped support for some older models (with older graphics cards on the whole), but since then support remains the same thus far.