I'm not very experienced either in the ways of
fancels.  I have commission from 2 different
artists and one is still in works.  

I really wished you would have asked this question
after I recieved my second one that is still in
progress.  It's quite a detailed shot and probably
a nightmare to make.  
For this one, I commissioned bakaneko :
http://bakaneko.donthurt.com/
Though I haven't seen what my cel looks like (it
is currently being painted) I was very impressed
with the work that I saw in her gallery.  She is
*very* nice and I think her prices are pretty
reasonable.

My first fancel was made by forkysanime :
http://www.geocities.com/forkysanime/
I was very happy with the results and they are
very nice and reasonably priced too :)
If you would like to see the sketch (which is just
as beautiful in my opinion) please go here :
http://nepenthe.rubberslug.com/gallery/inv_info.asp?ItemID=46685