I wanted to check one out before I posted.  I found a reasonable price at
www.grizzly.com for the 5" x 10' clear hose
(http://www.grizzly.com/products/searchresults.aspx?q=clear+hose).
With shipping it was $31.00.  So far this tube has been fantastic.  My
biggest boys can get through it and the smaller girls can curl up and
sleep right in the middle of it two together (to everyone elses dislike
cause they block the flow).
 
My big boys are thrilled to have a tube they can crawl through.  They
are old boys so crawling through is about as energetic as it gets.  Now
I feel bad for not searching for larger clear hoses before.  They did
have aluminum tubing and pvc pipes that were large enough for them.
 
On the grizzly order form they have a comment box and I mentioned the
tubes were for ferrets.  If anyone else orders from them, please mention
ferrets too.
 
hugs.  tle
[Posted in FML issue 5340]