Monoprice Outdoor Burial 8-inch Subwoofer with Dual Voice Coil (each) - Sycamore Series

I would recommend this speaker even if it was twice as much. It delivers a decent amount of bass. I have a big backyard and I have two of these in the ground alone with 4 rock speakers from Paradigm. It fills the backyard nicely. I listen to primarily rock/classic rock and it sounds good. If you listen to a lot of rap I would recommend something a little more robust such as the subwoofers that James loudspeakers have, but this are going to cost you 2-4 times as much.

You get a surprising amount of output from the subwoofer. So much so, than in a smaller patio setup, you'll have to turn the bass down on your equalizer. Get all 4 satellite speakers if you go with this. They aren't very expensive and going with 4 helps even out the sound around your patio and also helps them keep up with the subwoofer. Even though the speakers are weatherproof, I put planters over mine when not in use to keep them dry and hopefully live long lives. I wouldn't hesitate to recommend this to anyone. Its sounds much better than the price would suggest.