I'm also in the market for a 23" ACD. I've looked at the other brands and while it's tempting I find myself still leaning more towards the Apple brand. Plus, it also looks great sitting on the desk.
I've been watching e-bay like a hawk the past few weeks trying to spot the good deals. One thing I noticed to watch for is the contrast ratio; most are 400:1, however the last 23" model used 700:1. Further, at this point it's rare to see a completely new unopened 23" ACD. On average the used ones in great condition are selling between $320-450.
I'm kind of waiting a bit longer (until the new Mac Pros come out) to purchase one. I'm crossing my fingers that Apple will release new matte displays in the 24"-30" range here shortly, but I'm not counting on that.