Seems like that’d be hard to pull together in five days unless you plan on buying all of this in person. Do you have a leather jacket already? Because if not, then you’re probably going to end up shelling out quite a bit unless you get lucky at a thrift store.
As for trousers, you could look into Lands’ End’s tailored fit suiting. For a black tie, I’d suggest something from The Tie Bar, which should be pretty cheap.