The first wave of the RGB figures, the Ninth overall of the Diamond Select line, is now out in the wild. I saw them at my comic shop last week.
That first wave is Egon, Winston, and Slimer. The second wave (10th overall) will be Venkman, Ray, and the Stay Puft Marshmallow Man.
Sadly, the demise of Toys R Us means there doesn't seem to be any cheaper versions that don't have the diorama pieces, which I don't need. I see some of the diorama pieces on sale on Ebay, so I'm apparently not the only one who doesn't need them