http://caffenol.blogspot.com/
i mixed 1500cc of it in december
and was processing film and prints in it
with no change in consistency through march20
( probably 50sheets of paper and 50sheets of 4x5 film )
didn't replenish it, just kept using it.
i made another 750cc and removed some of the old and added the 750cc
and processed film in it a few weeks ago ...
and it worked as good as any "conventional" developer ...
probably the raw chemistry
( coffee, washing soda and vit c powder ) cost me less than 5$
and it lasts for a long time whether you mix it from dry ingredients or reuse it ...
have fun !
john