How many are there...let me try to think of them all...not at home so I can't easily count them.
-RA 2.0 red on white
-RA 2.0 white on red
-R3 white on grey
-R3 white on black
-R3 white on orange
-R3 white on light blue
-CCnG white on green
-CCnG green on white
-Black on orange (origin dunno. R3 perhaps?)
-Orange on black (origin dunno. R3 perhaps?)
-Monthly buy black on yellow
-Monthly buy green on blue
-Monthly buy red on white
-Upcoming Valentines set (Not sure if two or one styles)
-Not quite the same style, but the QWERkey white/orange/black
-Not the same but similar, Imstos reddish orange on grey
-Not the same but Keyboard Stories black on red
That's everything I can think of at the moment! There are some more, like the GH fundraiser modifiers, and the Cherry replica modifiers. As well as the WASD lasered caps. And probably some caps I don't even know about!
And as for that....I just need the RA 2.0 red on white folks!
EDIT-There is also an orange on black ALPS cap