Candy Buffet at E-Party??

our e-party is coming up in a few weeks and my FIL's are planning everything, etc.
i was thinking of doing a candy buffet! (yummmy)
but i dont know how much candy i would need, lol. i want to have plenty of candy to spare. so...

how much candy do you grls think i would need for approximately 150 guest??

and should i do candy bags, or boxes?? hmmmm
decisions, decisions...