I think it all depends on where you are located.

mr. Surfacer is not available in europe and they can be pretty difficult when importing paints etc. these days, so you'll have to look for something else if you live in europe.

Schmincke has a realy good clear primer for plastic and metal that is especialy made for airbrush.

You can mix it with their "Aero colors" to make your own color primer, or use it as a clear primer.

It's a primer for acrylic paints. It's called: "Aero grund" and is available in 125 and 250 ml bottles.

Schminke also makes fluid medium to make your own acrylic paint and the satin and matt fluid medium make pretty good dullcoats.