OBVIOUSLY! the weed is only such a ridiculus ammount cos weed smokers who buy from street dealers tend to be too poor to afford more but in reality ur being fleeced! think about it like this, every time u by a tenz draw ur paying a fiver for the weed and a 5er for the dealer to:

use his money to buy the weed
go and risk buying a shitload of weed from gansta types
weigh and bag the weed and get rid of he stems
petrol for him to roll down to your place
danger money for the fact that he'll go down if he gets caught
his time

all of those factors apart for the 1st are massively scaled down when u buy in bulk so in my opinion its not only foolish but also ur maximising the risk of u getting busted or involved in shit by picking up so often!

If u have the money, buy by the ounce and excercise a bit of self control (even if that means baggieing it up under your floorboards and only taking an eight out a week!)