If you do source the bentonite elsewhere just make sure it is food grade. I do not know if it is easily found outside of N.Amerixa, though kaolin clay would be an alternative.
Chitosan is derived from shellfish, typically the actual shells.
Kielesol is a silica gel fining agent. Chitosan-kielosol is a combo commonly marketed as SuperKleer. May want to check http://winemaking.jackkeller.net/finishin.asp
as this partcular link sends you to a page which provides a good overview of the various fining options along with cold stabilization, plus Keller's website is a nice resource.