Here's my formula for good "bang for buck." Look for speakers that are:
1. Local
2. Huge, impractical to ship.
3. Not yet "collectible."
My IMFs fall into that category, as do full-sized Frieds and TDLs. The Fulton "Modular" system is another, so's the pyramid shaped Sequerra (sp.?) speaker with the ribbon tweeter - there was pair on 'gon locally, for $600, for ages. Some of the older TOL Kefs, too.
How loud so you want to play, and how big an amplifier are you willing to buy?