"She said that she wanted to get back what she had spent on them. That is understandable but how can one expect to make the same amount that they put into a cel if they then separate it"
1) A spiraling market. A cel one or two frames off of my Sesshomaru cel (and not a better cel) sold for 4 or 5 times what I paid for mine (and then sold for two or three times what I paid for mine shortly thereafter)a bit after I had bought mine
http://tag.rubberslug.com/gallery/inv_info.asp?ItemID=92893
essentially because the market for Sesshomaru cels was out of control. (And still is, I think.)
It's not unwarranted in some situations to expect to fairly quickly turn around and sell a cel for what you paid for it while retaining the drawings.
(On the other hand, many buyers who buy when the market is out of control still want to "get what they paid for" when the market has crashed, and have ridiculous prices on their material. See, for example, brick and mortar animation art galleries and clueless "investors" in animation art.)
2) Purchase in one place and resale in another place. Anyone who considers themselves a dealer will by their nature be trying to sell items for more than they bought them for. This is true for dealers of corn, cars or cels. So, here we may have a seller purchasing from a source unavailable or too costly in terms of travel or informational barriers or quantity requirements to a certain group of buyers. The seller uses its access to buy materials and in turn provides access to the buyers at a cost greater (or so they hope) than their cost of obtaining the materials in the first place and at a rate great enough to justify their doing so instead of, say, waiting tables, practicing medicine, or whatever it is they might otherwise do. Some dealers may want their profit to be directly in animation art (there would be a tax benefit instead of converting the art entirely into cash, being taxed on that amount, and then spending the taxed money on other art); therefore, selling a cel at the cost of a cel and a sketch creates a profit equal to one sketch. Considering the differences in prices between cels and sketches, this is a fairly modest profit.
3) Parting out. The constituent parts of an item can often be sold for more than the parts as a whole. A laptop with no power cord or batery can be bought fairly cheaply. But someone who just needs its harddrive will be better off just buying the harddrive instead of the whole thing, and someone who just needs the RAM will be better off just getting the RAM, and someone who needs the keyboard will be better off just getting the keyboard, etc., if they don't want to go to the trouble of reselling the entire thing in parts. By going to the trouble of selling the parts to multiple buyers, a seller can make more than the cost of purchasing the laptop in the first place. Similarly in animation art, if someone buys a series of drawings, they may very well be able to sell drawings 1-4 and 6-8 cumalatively for much more than they paid and still have the nicest drawing from the lot, because while people were willing to spend more than the cost per drawing for one drawing, they were not willing to buy the lot and go to the trouble of reselling the other drawings.
You can combine these concepts; parting out is definitely relevant to the situation under discussion. Either or both a rising market (true for Sesshomaru and Inuyasha stuff in general) or purchase in one market and sale in another market (often true for anime art, I don't know if it applies here) may also apply here. It is not unreasonable for a seller in certain circumstances to expect to recoup their outlay for a whole on a portion of that whole.
(while this message appears properly in the editing preview, it is not displaying properly on the boards; length issue?)