I think patience and ebay are the best solutions. I bought one on ebay, but of course they're not terribly common. The one I bought wasn't even specified .833, but I could tell by the ebay photo it was likely a .833 by the way the quill was sharply necked down. I don't think the seller even realized it was .833, there was certainly no mention of it in the ad. For the $6 or so that I paid for it, I was willing to take the chance on it. It was an unusually tall stem, just what I was looking for. Good luck-