SVT28 the 4566, 5906, 5946 and IIRC 5944 all had small runs done in Melonite. I'm told there was also one 4506-1 prototype done in Melonite as well. All these runs of Melonite guns are quite small and those guns are scarce. When found they bring a premium over the standard models.
There was also 100 or so Shorty 45's that were made in black. A member here owns one. I don't know if it was a black coating or Melonite on those guns though. Shorty 45's ARE scarce. I don't know if anyone knows a definitive number on how many were produced. Counting the two runs of Shorty 45's plus the recently discovered run of black Shorty 45's I'd guess it is still under 600 guns total.
I couldn't hazard a guess on the Chief's Special models. I know the CS40 was discontinued first, so there will be fewer of those. The CS45 and CS9 were produced for LE orders for some years after the "official" end of production. While there were more of those CS guns made than the PC Shorty models, I wouldn't hazard a guess at how many were made other than to say they are rather plentiful in comparison.
My guess is that the PC Shorty 40's were made in the largest numbers as I see more of those than any other versions.
The NIB 3914 DAO's you are seeing are overuns from NYPD orders. Contrary to popular belief, the current company calling itself S&W still makes 3rd generation pistols for those customers who have no use for their plastic guns. (and for less than the astronomical prices that S&W apologists claim it would cost to make these guns!

)
The 3953TSW, 4566TSW, 5946, 4006TSW and 3914 are the models still in limited production for LE, that I'm aware of. However S&W won't sell them to the great unwashed. Who would buy their plastic guns if they could have a new 3rd gen pistol? So we are fortunate that some dealers are putting the surplus guns up for sale on the auction sites. Hope this helps! Regards 18DAI