Go to home depot or lowes or whatever they have in california(I haven't been there in a couple years) and get a tree in the gardening section. They have apple trees, peach trees, pear trees, plum trees, and lots of other trees. They are less that $20 usually and are between 4 and 6 feet tall. They can easily be trimmed to fit an enclosure and vine are easily attached with zip ties to give upper level highways. They do very well in my enclosures. Just get a tree that likes partial shade so they have less light requirements.
Justin