I might be a little unpopular here, but just remember that they are just trying to be responsible parents. At least they care what you are doing.
That said, instead of attacking their financial decisions; they are adults, make more more money, have probably already learned to respect money, and are allowed to spend their money as they see fit (I also assume that your lunch money was given to you by them...). It would be better if you just explained that learning to saving money for something that you really want is a financial lesson. Tell them that if you learn to save for things now, you'll be less likely to depend on credit cards or loans later. I think this is a better plan of attack.
(By the way, I'm not a parent or anything. I just speak as a son who, since moving out to go to school, has learned to respect my parents a little more than I did.)