I’m one of those people. 
Well, except that I never buy in bulk like that. See here. Pictures.
I average 60+% savings on name brand products. Today I ended up with 4 free quarts of soy milk and 7 pounds of yummy pork chops for $7 .. instead of $30. 
It’s all in playing the game and knowing the right sales at the right stores.
Uhh.. and the comic’s delayed while I letter the strips right now! (While watching Death Note.)