If it's not going to boom, it's going to come in a big box. And
probably cost rather more than your budget.

Mission offer this
http://www.mission-usa.com/index1.htm

But it strikes me as a home-cinema toy. Cheap though, so might be
worth a listen.

Remember the rule of sub-woofers. If you can hear it, it's turned up
yo loud.

Thank you for the info. I will give the Mission a try.

What do you think about subwoofer's like: Yamaha YST-SW225 or Yamaha
YST-SW325 (they are around 230 pounds/300 euro)?