I think you should consider DIY, or maybe check SONY SA-WM40 or maybe Audio Source 15. Although the PB12 isnt a bad sub. I only tested it with movies, not music.
I have had the PB12 for almost a year now, and couldn't be happier. I paid $299 delivered from J&R. Although it can be boomy at times if not properly setup, it still does a tremendous job @ 50/50 music/HT. When I want to listen to music, I just turn down the output to the sub on my receiver a little, since I run it a little "hot" for movies. Placement does have a noticeable effect on the sub as well. When I first got it, I had it in a corner, about 8-12" from all walls. Now, it is beside the couch under an endtable. Overall output seemed down a little, but sound quality increased. I run it crossed over @ 80hz through receiver, with the gain on the sub amp at the 12 o' clock position (halfway).