I've thought abou going for complete library sets on some of my favorite consoles, but honestly I have no desire to own crappy sports titles and horribly made budget titles. I try to keep my collection as high quality as possible, which isn't to say that every high quality game is in my collection or will be, but I only want to obtain games that personally interest me. I'm reaching my limit with that. Even after that point, I'm sure I'll still run across games that I overlooked at one point, but decided to give them a chance. This has happened with several XBOX and Gamecube games after I finished these collections.
I started out as a "buy anything and everything" collector but I found that to be an empty endeavour at least for me. I really began to hate the idea of shelves and shelves of "filler", games I knew I'd never play. My collection is now much smaller but contains all games I really love and play. It's different for everyone but it seems to me that eventually, most collectors come to the same realization sooner or later and purge the filler in their collections.
I've got elements of being both a completionist collector and a focused collector. For, say, the Virtual Boy, I want a full set of the games. For, say the Playstation or SNES, I'm not interested in uber-common stuff like annualized sports games, and I tend to ignore sports games everywhere I go. These do not inspire me to spend money.
I even told a real crotchety mom at a garage sale, who was way over-charging for a Genesis and a Playstation, that all the games she was including in the price are sports games and that they're worthless.
