@papatrop: Well, thank you! That's exactly what I was looking for and exactly how I feel about something like the Naga. I mean, I don't use that many hotkeys on the keyboard, where the keys are much more spaced out and easier to press simply because, even in something like Skyrim, I only use 5-6 different spells regularly so no use for 12 buttons on the mouse alone. Then, there's the muscle memory question like you've said; instead of having to break away from the game to find "9" on my keyboard where it's much easier, I break away to find a tiny "9" on the mouse.

If it's with regard to desktop functions only, does X-Mouse not do the same thing for free? Check this video where the guy can basically choose any mouse button to do literally anything, such as acting like the number 5, zoom, and anything else:

https://www.youtube.com/watch?v=-sKV5Yb2160

To both you and to @PredatorRules: (Predator, since I am also looking to buy a tablet with only one USB port that's not position very well, I was actually only looking at wireless mice with Bluetooth so that I can use it on my tablet as well - guess that's why they were more expensive than what you were referring to...) I am actually even more of a budget shopper! The one I linked to in my first post was only 13 and with two extra buttons to serve my needs as hotkeys and changeable dpi to somewhere around 2000 (I've forgotten the exact specs), I am happy enough. I should try out one of the more expensive mouses like the ones from Razer to see exactly why people buy them...

Anyways, thanks a lot to everyone who helped me out with the question!

@PredatorRules: Take the example of those Razer mouses. They're well above a $100.

No one seems to have answered the question; if any mouse has more buttons than the normal clicks and scroll, can they be designated as specific functions in a game or does it have to be a mouse that comes advertised as "programmable"?

I am currently looking to buy a new mouse and am really confused by the extra buttons. The mouse I am looking to buy has two extra buttons for backward and forward in browsing but can I also set them up as hotkeys in games (like numbers keys correspond to a specific spell or weapon in Skyrim)? Normally, you can set any button as anything in a game but, then, I look at these $100 mouses which come advertised as having "programmable buttons" and I can only think of the higher DPI and the inability of the mouse I am buying as the only reasons of commanding such a premium.

I also came across some software called X-Mouse which seems to allow any mouse button to be substituted as anything else so does this mean that while the $100 ones support this from the get-go and I can still buy the cheaper mouse and use this software to set those extra side buttons as hotkeys?