Cel prices depend upon supply and demand. I 
would not enter into it as an investment. I 
started in 1998. Good SM cels were $100- $200 
then. I collect because I like the art. I prefer 
to have one or two good cels from a show. I have 
never sold any of my cels. Really good cels 
don't return to the market frequently, so they 
tend to retain their value. I have said this 
before and gotten slammed: It is a bad idea to 
buy cels thinking you can get your money back. 
Consider it as if you went to a really good 
restaurant or a Broadway show or an Eagles 
concert or even a vacation.. you felt good while 
spending the money and you can't get it back. 
So, be happy that with cels, because you can 
actually get some money back!!!