Limiting your collection to only the chips you like is a very good idea and that is one of the major points I always tell new collectors. I have taken in a lot of chips in trading that I would not have purchased for my collection but they were chips I did not have in my collection and my thinking was I could always sell or trade them for chips I really wanted.
How do you determine what X is going to equal? How much room you have in your wall display, or how much room there is on your shelf for chip binders?

I am retiring at the end of the month and I have decided to sell off parts of my collection to specialize letting one part pay for any new chips.

In my experience quality equals $$$$$. How much of a consideration is that?