It's hard to gauge her price since there's never been one like her sold
IMO, the only way to get a real sense of her value would be to take offers and see what the highest bid is.
As for the other ponies, feel free to make a thread here asking for a 'Price Check'.
People will give you their imput on how much those ponies have been selling for lately. It's always a good idea to ask for a PC before selling if you've been out of collecting for a while since prices can fluctuate all the time.