they are all about the same
http://www.harrietcarter.com/index.cfm/fuseaction/product.detail/_/Doggy-Steps/p
roductID/1C3CF334-2132-4BC0-9C04-434D7F1E7A82/categoryID/68D0271B-6300-4227-AD66
-5A6C6B87E483/

you could build your own for a few dollars

I used 3 milk crates zipped tied together and got some of those plastic
containers from the dollar store that where half the size zipped tied them
all together and used them as steps cost about 7 bucks

I have never used one, but Drs. Foster and Smith have some that look very
nice.  Everything I have bought from them has been good quality.  (I looked
carefully at their cat stairs when I was making arrangements to adopt Duffy.
He is blind, and I (incorrectly) thought that I would need to make special
arrangements for him.  I soon learned that he can do *anything* on his own.
He loves to climb, and cat stairs simply were not needed.)

MaryL

Photos of Duffy and Holly:      >'o'<
Duffy:  http://tinyurl.com/cslwf
Holly:  http://tinyurl.com/9t68o
Duffy and Holly together:  http://tinyurl.com/8b47e