P90s are a love or hate gun. Its best to try one out before laying out a tonne of cash.
If your doing lots of shock and awe CQB with short engagements then they are the cats meow.
They get to be a pain when you start burning through a bunch of mags (horrid mag changes).
All in all I think they have a place in certain peoples arsenal. I would like one myself, mainly to use alongside a bolt-gun.
A CA Sportline or Echo1 would probably fall reasonably close to your budget once your AVd.