Just gotta be persistent. I got lucky and was able to snatch one for $450. I saw one listed for $450 and asked the seller if he would take $420 shipped and next thing I know the listing was gone. I emailed him back and was told it sold before he saw my offer.
I was disappointed until he mentioned that he actually has one more and will be listing it up the next day. I told him to inform me before it goes up, and right after it went live I purchased it immediately. Didn't want to take any chances as I missed the whole provantage deal and a few others on ebay.
I noticed some people are selling old PCs/Servers with W3680 and W3690s in them at bargain prices. I saw one for $350, but it's been a while. Anyways good luck in your search and try not to over pay.