How do you proceed if your opponent makes an Unusual move,

Would you continue on theory and hope there move doesnt matter. Or would you look at it for a while and try to come with a completely different plan?? Any advice?

Opening theory is based off of responses to moves, that is why there are so many variations.

If your opponent does something "unusual" you are no longer in that line of theory or if it is early enough it could just be a transposition that will result in the same position eventually anyway.

Best thing to do is to look for a logical move that grabs space, develops pieces, or makes threats and after the game look up common responses to that move. If you don't find that move in the database then think about what is weak about it that causes no one to play it.

I'm not continuing moving on to theory without knowing the ideas behind that move. That's why I just studying the basic ideas of the opening and rely on my own judgment rather than book moves or opening theory.

The theory move usually contains the reasons why the other legal or even logical moves do not make sense?

So if you get a good memory of a theroy, u usually know how to punish an untheroy move?

How do you suggest doing that, without buying a book for each opening?

You can look at grandmaster games, but it's sometimes hard to know the point of a move without it being explained. I don't know of a good source for annotated master games by opening.

Look at each move that is made by the masters.  Are they trying to take control of certain squares or is it a tactical operation(if it seems to be this then plug it into a comp to figure out why certain things are wrong or right).  Taking control of certain squares, color complexes, files or ranks (and especially if this coordinates the pieces against a king)are generally the basic ideas if it isn't a tactical operation(or sometimes if it is), sometimes even at the expense of material. 

You can also just do a google search for a specific opening and there are a lot of free resources in general on the different ideas of openings(some better than others obviously)

You could just look at what the move objectively does, what it objectively prevents (i.e. 1. Nc3 prevents playing 2. c4), what it discourages, and from that you can probably get a good idea of what that move encourages from you a response.  In fact that's probably better to do first than searching for a grandmaster or a master's opinion.