Big G3/G3.5 = Styling pony
Big G4 = Fashion style pony
I have seen the G4s called styling, but never G3s called Fashion until today. :I
There are also G3 Style ponies. You do not see them very much though.
I have seen loose Rianbow dash ones go for $7 to $10 on here.
I have not seen a pinkie pie for for a while though.
There was a loose Rairty that went out for $19 on ebay a while back.
Cant not say that they are very popular. I have not seen to many of them for some reason?