Is your DSi an XL? There's a blue one of those. (darker than the ice blue DSi, so some may see it as a dark blue)
My red DSi is rare for where I live, since it's only available in Japan and Europe. ._.
If there is no Red 3DS, I will get the purple one as that will sort of match.
That's if purple is released as a colour. It was one of the show colours at e3.