Jeff's pretty easy to do on the cheap, I think that the most expensive thing might be the hoodie or a wig (if you choose to get one anyway, you can temporary colour your hair using different products).
Luckily I already have a white jacket that I'm probably not gonna use for much longer.. since it has 2 holes in the hood. D: (It's like, my favorite jacket even though its just blank white) My boyfriend does not approve of the jeff idea but oh well xD
The one that I'm using in this picture is just a plastic one from a costume store, I haven't been able to find a more realistic one unfortunately. Again you can probably find a prop knife online if you can't find one in a costume shop.