Don't look for Anavar, that is a brand name manufactured by Searle Labs and is no longer being produced or is temporarily not being made. Look for it using the generic name Oxandralone.
Oops, sorry Nahanrac, your post wasn't there when I started to type. That's what happens when you visit this board while your working and going back & forth between the two.
Its too hard to say. It all depends on genetics, diet, training etc. Huck put on 12lbs of solid muscle. I would say between 8-15lbs. But remember you will lose fat also.