Hard to find good subs for 400 unless you hook up with Adire Audio's Shiva. Forget all the commercial stuff unless you spend over 1K. I've been using Shiva for 6 months and I couldn't be happier after spending about $400. It is both musical and dynamic (for home theater). I built my own enclosure which saved some money but you can find pre-finished enclosures at reasonable prices. Look up acoustic-visions.com. They have the price range you are looking for. Also, see the reviews on this at audioreview.com