I was wondering what the forum's opinion is on jerry cans. I reckon I'll need 4 20l ones and they would go on the roof rack. Is there a reason to go for metal cans if I only intend to keep fuel in them for a day or two at a time? Will jerry cans release fuel fumes? And where's a good place to buy them cheap? I've seen the metal ones for as little as 30$ when on sale.

Cheers!