polk momo dvc 12" sub in a sealed box. spend roughly 150 on a monoblock amp. add wiring and a cap. under 450. will pound. have a momo in my boat that fucking beats hard. would love to put it into a hatchback to see how it acts. honestly skys the limit, but spend most of your money on a decent amp. a shitty sub can sound good with a decent amp. sonicelectronix.com