I and others have posted this solution a few times on this list, but it bears repeating.
If you can't find art paste, use the clear wallpaper paste that you can buy at any big box store or hardware. It comes powdered, just like wheat paste, but is much better. It is made primarily from wood cellulose, and is far superior in strength and longevity to wheat paste. Another form of this is already mixed up as a liquid paste in containers. This is the same stuff, but is too thick to use as paper mache paste without adding water, but it will still work. Some feel this paste is not strong enough when dry, and if you need to, add white Elmer's glue to act as a hardener. Starch and flour pastes are OK, but just barely, unless someone has a recipe I haven't encountered.