I think you should listen to some stuff at some electronics shops and gather some knowledge of the type of sound you like. High quality speakers will sound VERY different from each other, but also from those hand me down disposables you have been talking about. It will probably take a while for your ears to adjust to what a better set of speakers will sound like, at first it may be wierd to your ears, and the set you get from the internet, sound unheard may be unfairly judged when you don't know what to expect.
If you go to audition a few sets of speakers ask to hear speakers that are in your budget to get an idea of what to expect for your money. If you have access to a cd burner (most of us do nowadays) go burn a disc with a bunch of your favorite music on it so you are intimately familiar with what you are hearing, I bet it will sound like brand new music you have never heard on a good set of speakers (unless it's rap, but even then it will still sound better).
The telltale sign that you have found the right speakers is when you are listening to a song that you are used to, but it sounds so good that you get chills of excitement, because you just heard an extra voice or instrument, or even a whole other part of the song you never knew was there. My system is not that special at all, it probably didn't cost me even as much as you are budgeting for speakers, but even with my modest setup I have expierienced this many times over, I tell you it is an addicting feeling.
Then again, maybe I'm all just too passionate about good sound...
-Mike