You could get a very decent 12" for 400 dollars, or you could get two good 12's for that price as well. Since you listen to a wide variety of music, I would asume you would predominantly want an SQ sub with good SPL if you want to pound on occasion. If you go for the two 12's, look into Infinity Perfect, Alumapro Alchemy, Image Dynamics, there are way more, but you can look them up. You could get an Eclipse al 12 for 400, which would sound excellent as well.