Can you describe what exactly is going on that makes you think your current speakers don't "hit it?" for music? I ask simply because it will help dictate whether or not you need new speakers or if you simply need to tweak what you currently have. Or if you get a whole new setup, it will help determine what you might need. So what size is your room and what kind of material in the room (carpet, tile, etc)? What's missing in the sound currently?
For music, and with your budget, you could go towards a nice set of book shelves, or even some entry towers. Either way will probably sound a lot more full and lush and less boomy than your current setup for music. As it is, a lot of the work is probably being done by that woofer since those satellites are 4" woofers basically and cannot dig that deep, so the bigger woofer (which they market as a `sub' woofer) is doing a lot of the work there and probably is boomy I imagine. Get some book shelves or towers that can do more range and it will probably in general sound a lot better depending on your room.
The BX2's are nice, but maybe you can find something with two woofers and a tweeter or horn instead?
I would personally try to sell your current Vector setup, keep your AVR, and re-build a 2.1 setup and expand to surround as you can afford it. I say that because mixing and matching new speakers with your current satellites might not sound very good as they're not going to having matching tone and signature.
Source: Pioneer VSX1121 (shopping for an amplifier(s))
Fronts: Polk Monitor 70's x 2
Center: Polk Monitor 70
Side Surrounds: Polk Monitor 50's x 2
Rear Surrounds: Polk Monitor 50's x 2
Subs: Polk PSW505's x 2