The best case that I have found came from Wilson Leather. I don't know if they are national or not. I checked their web site and couldn't find my case on their webpage.
The case is black leather and has an open sleeve on the left side and a pad holder on the right. What I like most about the case is that it doesn't require a velcro patch on the back of the Palm for attachment. It is held in place by a strap (unobtrusive) at the top of the pda sleeve.
Inexpensive pads are available at Staples and OfficeMax. The case cost about $25 and is very well made.
Good Luck (I am still in search of the perfect case/agenda)