I am reasonably certain that the NIB 3913 purchased at a garage sale for $10 is pure fiction. Not that I am a garage sale kind of guy BUT I have met a few of them over the years. And I can't recall any of them talking about buying any kind of guns, let alone something that was new in the box or for $10.
That's just my .02 worth. Okay. I'll go up to $10 but not a penny higher!
Oh, and I almost forgot. Congrats on the CS45. Sounds like you scored a beauty!