I did get the celltei backback (they had a 20% off sale last month) and I love it as it converts from shoulder bag to backpack. I'm sure they didn't intend it, but is works as a front pack which is great for taking the little munchkins on the ATV.
Just saw one in the Jeffers Pet Supply holiday catalog for $23.95. Let me try to link -
Travel Backpack If the link doesn't work just go to jefferspet.com and type item I7TA67 into the search. Too bad I didn't spot this one first!!