I agree. Start trolling WUS and TZ...you'll be amazed of what you can find for $600. I've seen ENZO MECHANAs going for around $600 this year. I have two of them, and I wish I was able to get them for that low.
In this price range, I would check out DIEVAS, Benarus, Artego, and last but not least the Boschett Cave Dweller! The Cave Dweller is next on my list!
Happy hunting!