I have been thinking about getting a new subwoofer. I am replacing an old PSB Subsonic II that I have had since college. But now that I own a house and have other projects that pop up, I am looking at the DIY option in the hopes of saving some cash. I am confident that I can handle the actual building of the sub. I just need some recommendations for components. A buddy of mine has a DefTech SuperCubeII. It sounded pretty good to me. The problem is I dont really want to spend that kind of money. I would like to stay in the $500 range when building mine. I realize that any DIY sub would be much larger, but that is fine with me. It can be bigger than my current 12", just as long as its not monsterous. I have looked at many different drivers, amps, and box recommendations. I just want a good opinion from someone who had built one. Here is what I have to work with, $500-$550, 99.9% used for movies, my room is 13 wide X 17 long, with 8 foot ceilings. Any help would be greatly appreciated.