How much doees a banquet hall cost?

I'm planing my sweet 16, and i wanna rent a banquet hall. But idk how much it's going to be. I don't want to pay per plate. I know some places do buffets, i want to do that. I'm inviting around 250 people. I also want to know about barattending and the decorations. Do they charge extra? *** if possible explain every little step they do. (: thanks so muchhh :-* ♥ Btw i live in northern new jersey. alot of people say it depends on where you live, to how banquets charge.