Rusty,
The four inch 610 will be part of S&W's standard line. Cost right now on a 6 1/2" 610 is about $480(+/-) and if I remember correctly, there will be a 6 or 7 percent price increase Jan 1st. A good, competitive dealer will only mark up 10% over cost plus shipping.
I have a weakness for two material things in life, bikes and guns. And the best of the best in these categories are fine Italian bikes (any kind!) and S&W N frames. I'm just a S&W "Ho". Can't help it!
Robert