I would say there is not a set amount. IMO your feed bill is "too high" when the net draw on your household funds stresses your ability to allocate the appropriate monies to other areas -- bills, groceries, savings, etc. That may be a very small number for some people, a very large number for others.
Well, jackrooster, I see that you have over 50-something chickens. Your parents pay in the neighborhood of $36 to $50 per week for chicken feed. At most this averages to $1 per chicken per week -- that's like... chicken feed!
I just feed regular layer pellet.......12.00 a bag..........over 50 chickens divided into 3 flocks......breeds consisted of silkie,brahams,cochin bantams,buff orp,SLW,GLW,barred rocks,black auprs,phenix,EE, 2 RIR's, red shoulderd yomacka, and i think thats about it...?