Experience is the only teacher when it comes to 
how much is the going rate of certain cels. It 
depends on the series, the character, the quality 
of the shot, what comes with the cel (meaning 
sketches, backgrounds, timing sheets, genga, etc) 
as well as various other factors. Combined with 
that is how much it is worth to *you* personally?

There is no price guide for cels.

Here is how to learn the going rates of certain 
cels: Go to every dealer you can find and compare 
prices. See what cels are being sold for how 
much. Make notations of the quality of the shot. 
(Some things to notice: Are the eyes open, closed,
or half closed? By what degree is the charcter 
facing front? Is the character in the middle of 
some weird motion or "interacting" with nothing? 
Are the paint tones used in the cel the "normal 
light" colors, "nighttime" colors, or "special 
light" colors?) Does the cel come with anything? 
Is the cel oversized, if so, by how much? Is it 
from an earlier or more desireable episode?

Also, when looking at prices, you have to 
consider at which dealer's site are you looking? 
Is the dealer in Japan, the US or somewhere else? 
Does the dealer tend to be more expensive, less 
expensive, "hot and cold", or right down the 
middle of the road? (As a tiny guide, some of the 
more expensive dealers include Noonchester and 
Asylum, some of the less expensive include Chaos 
and Anime Shop Vi. Taro can be "hot and cold" on 
their pricing, but they're generally towards the 
good end.) Also, you might want to ask people 
what they think of certain dealers. You may see a 
pile of really nicely priced cels on a certain 
site only to find out that the cels are sitting 
there because people don't like the service - or 
lack thereof - that they get from the site's 
owner. (Mangaya comes to mind.)

The last thing to mention about pricing is that 
more often than not, YOU GET WHAT YOU PAY FOR. 
Maybe you see two similar cels from the same 
sequence, each on a different site, one for (as 
an example) $10 and the other for $50. The less 
expensive one might NOT be less expensive because 
the dealer has better prices - it might be less 
expensive because it's damaged in some way (which 
can include anything from a greater number of 
abrasions on the surface of the cel, to missing 
pieces of paint).

There are other reasons to go to an "expensive" 
dealer's site. Maybe that dealer carries some 
series that others don't. Or knows about an anime 
that other dealers aren't as knowledgable about. 
(Trust me, when you're looking for cels of an 
obscure character, it's worth the extra money to 
*NOT* have to write a 500 word essay when asking 
a dealer if they've seen the character. ^_^;;) 
Maybe it would be beneficial to form a 
relationship with a certain dealer because they 
seem willing to look for things for you, or will 
offer things to you privately. (And believe me, a 
dealer that will privately offer you cels you've 
been looking for - instead of posting them to a 
public site where you can easily miss out on 
them - is WORTH THEIR WEIGHT IN GOLD!!)

So as you can see, it's pretty complicated. ^_^;;

And just so you know, I have personally ordered 
cels from every dealer I listed above. And with 
the exception of Mangaya (putting in an order to 
them is only for the most patient and stong of 
heart), I would highly recommend them *ALL*. ^_^

Many Sharp Smiles,
--Drac