Audiophile "PA" System??

Here is a new idea:

Health and fitness for me is discipline that goes in and out of favour, but when I do work out, I really enjoy listening to music.

In general, the iPod has been a breakthrough device for this application, but I find headphones a bit fatiguing and claustrophobic.

So I am wondering if I were to set up a small gym at home, what type of system would be reasonably priced, robust enough to withstand a bit of sweat and vibration, and be able to play loudly and sometimes over the din of exercise machines.

Of course, at the same time sounding as sweet and musical as possible and having decent bass response. Can't go jogging to baroque chamber music.

Any thoughts?