I'm sure Mike Janke will respond to this, but, just in case:
 
For Ferrets Only carries a full shelf which fits the Midwest cage.  They're
the ferret store connected to the South Florida Ferret Rescue in Miami.
The phone # is 305-378-8877.  I ordered one for my cage.  It's a little
difficult to install but, once in, works great.  My babies now have a full
shelf at the top in addition to the two small shelves and ramps which come
with the cage.  I think it was around $12-13.  I will warn you that the
shelf is wire so you'll need to cover it with something.  It's quite a
challenge to figure out how to place the ramps and original shelves so it
all works, but if I can do it, you can too!  You can email me if you have a
problem with it and I can tell you how I set mine up.  Call and leave a
message for the catalog but also mention you're interested in the shelf as
it wasn't in the catalog.  Angela is the shelter director and handles all
the orders too (very nice person).
 
You can also order extra shelves (same size that came with the cage)
directly from Midwest but it costs as much (or more) than the FFO full
shelf.
 
There's been no such Ann Landers column in the Tallahassee Democrat in
recent memory.  I read AL every day.  Maybe it was an old column??  It
would have to be VERY old for me not to remember a column about ferrets.
 
Katharine
[Posted in FML issue 2500]