I work for a sign company - as a graphic designer. I would recommend a minimum of an avery 800 vinyl, with 900 being the better option.
Decals such as this can be produced very very cheaply. For longer life request a vehicle grade clear laminate - which should stop any harsh fluids or heat destroying the film.
try finding a copy of the logo from
www.brandsoftheworld.com and giving that to the sign company - should make the decals even cheaper!
I would expect no more than 10$ for 2 decals like that...