I always buy washing powder in massive boxes from Big W, diswasher tabs in bulk and huge bags of dog food. Things I only buy when on special are: shampoo and conditioner (I am sure my teenaged girls pour it straight down the drain, they couldn't possibly use it on thier hair in the amounts they go through!), toilet paper and tissues, sanitary napkins (again two teenaged girls) and soft drink in cans and of course nappies.
I am bit worried that I should get a hobby other than checking out the junk mail to see what I can get on sale! My DP thinks I have gone mad too.