I would think if you were selling Sunny Rays you should do so sooner rather than later as she can be purchased right now for pre order [MIB and with her little accessories] for about $6-7 so she wont be worth more than that price for very long.
Sweetie Swirl is a different story as she is a pain to track down without having to pay for the whole playset plus the shipping - so if her recent ebay auctions are anything to go by people will pay much more for her.