Hi, I have just been round to a mates house and he has a hifi with a stereo speaker set up. It has a big about 12" subwoofer at the bottom and a supertweater at the top and also in a middle a normal speaker cone about 4". He has 2, and the bass can make the room shake. They are big, like up to my waist in height and also about 60cm or so deep (24"). How much do these speakers cost and where can I get them from?