Speakers Needed: Audiophile Taste - Low Budget

I am looking to upgrade my current HT system's speakers (fronts & center). I have the taste for high-end speakers however, I have 3 children & a new home. In other words I can not afford much, $500-$1000. I am looking for bookshelf speakers for mains & a center channel. I would like to get the best possible sound I can, (clearity & accurate tones - easy to drive). My receiver is a Sony STR-BD930. I have a good sub & rears. I prefer to purchase used so I can get the best speakers for my money.
Can some steer me in the right direction? Any comments are encouraged.