WTB: 10" Sub Woofer-new or slightly used

Jayhawks4

I am new fairly here and looking for a nice sub woofer at a nice price that would give me good service. Recently purchased a 46" Sony HDTV. I have added a new Yamaha YSP-1100 Sound Projection System that I have not received yet. This is a rectangular box containing 40 small speakers and two woofers and is 120 watts of power. I have been told I need a sub woofer to add on for optimum sound. The sound projection system is not cheap so I am not looking to spend any more than I have to for a nice sub woofer that would do the job. I have been told I need one 10" and at least 170 watts of power. If you have something reasonably priced that would work fine for me with this system, please let me know. Gary