I agree with Karen L.... how the hell are we supposed to know? And what do you think Google is FOR? God help whoever you are organising an event for... sounds like you couldn't organise the proverbial piss up in a brewery
How can anyone possibly tell you? We don't know the size of whatever-it-is, and prices are not the same everywhere. We don't even know what country you're in. Call a place that does such things and ask them.
How much does it cost to hire lining from a marquee to cover a village hall or barn etc?