I could be wrong, but I get the feeling the blonde version will be the final variant, given the fact that she's called the "Morning" Mermaid, as we now have:
Evening (auburn + teal)
Midnight (dark brunette + purple)
Morning (blonde + crimson)
...Unless they want to surprise us with:
Noon (ginger + pink)
Afternoon (red/maroon + green)
I wouldn't complain and yes, I'd buy them all.