What type of hair dye should i buy that's cheap, easy, not permanent, and blue?

Manic Panic

What type of hair dye should i buy that's cheap, easy, not permanent, and blue?

Walmart sells some blue dye that's pretty cheap.

As does hot topic.

What type of hair dye should i buy that's cheap, easy, not permanent, and blue?

For the love of all things holy, please don't even think about touching Manic Panic. I don't know a single person in the world that their hair has stayed dyed the correct color for more than a week with that crap.

As for not permanant- it's not going to happen. You have to open the pores on each strand of hair with bleach before you actually dye it. The dye then adheres to the open pores. As you cannot do temp bleach, you can't do temp blue. I would suggest spray color if you are only using it for halloween or something.