Katie- I agree, the blue is a tad too bright for my taste, and I think Navy is what her blue actually is. If the wig was a few shades darker, I feel it would probably work. So if they make it darker I'll consider it, haha.
And Haley: (is it ok for me to call you by your first name?! I never asked!) I can't see the pic, but what I saw from the link's description, it seems like it would work. Sharpie dying is a lot of work for a wig of that length, but if you can find the time, it will probably work really well! I'd suggest washing it a few times gently after you dye it, only because sometimes the dye can rub off and stain your costume. And I think rather than poofing the wig, just styling it and cutting it might help with the weight? Oh, and if you make the horn into a clip, you could clip the horn into the wig cap and the wig, which would help support the ponytail? Sorry I rambled, me and my opinions, haha! xD;