I'm going to go the other way and say: Hide buttons that are unnecessary. Keep the visual bloat as minimum as possible. To me, a disabled button means that I need to select an option to enable it. An example of this is to check the "I read and accept the EULA" checkbox, which must often be checked before the Next button becomes available. Another example is choosing what you want to install, and when nothing is checked, the Next button will often be disabled.
In this case, the action to enable the button is not available within one screen, but instead the user must travel through multiple screens to enable it. In my opinion, this means the Save button should not be on every page.
The standard option, used in most installation packages or wizards, is to replace the Next button with Install (Or in this case, Save). To to me, that's the best option.
This will also cause less confusion for customers, as they won't have to worry about what Save does and actually means. If the Save button is available (even if disabled!) on every page, the button could have multiple meanings, like "Save progress within this Wizard". Seeing as you don't want that confusion, I see hide it or use the "industry standard" of just having Back and Next, and replacing Next with Save on the last screen. (Just like the first screenshot in Zoe Kulsariyeva's answer by the way)