This is one area of our hobby where you can save money, any Auto shop will sell you a spray can of primer and it will be as good as anything AK/TAMIYA et al sell,
I swap the spray head for one from a can of modelling paint to ensure the spray is finer than a truck fender would get!!, I don't know what you are painting but just in case you are not aware German Armour used a red primer. shaun