Cels of Shampoo are highly sought after, so you 
could probably get about $300 for that one alone. 
The long haired Akane is also a rarity and should 
bring in a good price. Ah! My Goddess cels are 
generally expensive, and you've got two nice cels 
of Skuld there. Along with your other two... I'd 
say $1000 - $1300 if you sell them seperately. If 
you sell them as a collection though you may get 
less. Somone may be willing to pay a lot for cels 
from certain series, and then just pay a little 
extra to take the remaining cels off your hands.

~Lina