If it's helpful to you at all, I recently purchased an SSDMR4B on Ebay, thought I'd share my experience. They've seemed to run about $35-45 for the most part, plus $5-10 for shipping. If you're not fussy about colour it will be easier to find a good deal. I had watched for one on this board for a while, and most guys offered them at decent prices but they always seemed to get snapped up before I could get one.
If you're interested in alternatives to the SnapOn models, the Williams model is similar, and there are also CaseIH and NewHolland branded versions that are SO sourced but made overseas that are available for about $25 from your favourite CIH or NH farm machinery dealer.
That said, SSCustoms, that's a nice screwdriver. Almost makes me wish I was still in the market for one!