Here's a recent example:

I asked about the availability of a cel on Dec.  27, 2002
and
on Jan. 31, 2003 I received a reply.

I've only bought one cel from them and that was a long, long, long, time ago.
If your cel is indeed unsold, (many sold cels are still sitting on the site, many 
not even marked as on hold) and you buy it, you will get it, how fast is the real 
question w/ mangaya.

Oh and read this thread or at least Drac's post.

The wise words of Drac:
http://www.eu.animanga.com/db/celsarchive5/cmd=thread&aid=76099930906318696&
template=show.html&query=ID='76099930906318696'&var=tstart=1&var=tnb=30

Hope that helped,

Kelly    -_^