If the user name's anything to go by, it's being sold by a fireworks display business. The seller seems keen to show it working, so no need to part with any cash until you're happy with it. If in doubt, take a couple of friends along to make sure you don't get mugged for the money, if you think that's a risk. I'd consider bidding, as it looks like a good deal, but I'm skint at the moment!