YAY! I just won an auction for an Infinity Reference 1030w for $10~$20S/H
if you don't know, it's a 10 inch sub that takes 1 cubic ft, 250w rms 1000w max and it's one of the tightest cleanest subs I've heard in it's price range.
the box I'll make for it will fit under the power bench in my van and should be enough bass to make me smile without deafening the kids. also, my father in law drives and rides in our cars and HATES bass, thinks it's a waste of space and will ruin your vehicle (somehow)
so he won't even know it's there.
edit: I'll be pushing it with a Kenwood Excelon KAC-X401M class-D Monoblock amp that pushes an easy 600watts RMS @4ohms