S&W makes their revolvers in batches, so they may only make 642 Pro's a couple, three or four ties a year. It will also depend on where your dealer gets his S&W's, some distributors get more product than others, depending on how much they have sold recently. S&W sells more 642's than just about any other revolver they make.
You can also use Davidson's "Gallery of Guns dot com" to see if they have any in stock and then use their Gun Genie to get quotes from local dealers.
By the way, I bought a 642-1 Pro recently and the trigger is better than my 642-2 in which I replaced the hammer and rebound springs and dry fired about 2500 times.(lost that one to my wife!) The Pro is sweet right from the start. Moonclip cut cylinder is cool too.
Got a 442 Pro 3 months back and it's been great (stainless cylinder and barrel) So just like the 642, only black and cut for moon clips too. Bud's had them in stock as recent as last night when I was at their retail/range shop. Though I am thinking of trading to a M&P 340 for weight, but the 442 pro is niceeeeeee.
Thanks for all the Info , got one from Buds , went to the range yesterday Little bugger is a hand full with Plus P's 150 rounds w/ standard 38 , was ok could put all 5 in a 6 inch pie plate Nice weapon .