What about the Xeon E3100/E3110 in LGA775?
I read that these are direct drop-in replacements for the E8400, they just say XEON on the outside.
So far I'm seeing prices of $195-$220 for these online, and plenty of availability.
BTW, I put an E8400 in my shopping cart @ Tigerdirect right before I left work last night. I got home and tried to finish my order online, and the E8400 was REMOVED from my cart and no longer available. Every place I saw that had the E8400 in stock a few days ago is now out of stock. About the only option now for one of these is buying it from a no-name outfit for $275+ or from Amazon @ $300.