Any of the " lacquer acrylic " rattle-can primers you can get at the big-box stores or auto parts stores . ( look for spray paints recommended for plastics )

Also the modified alkyd primers like Rustoleum's 2X , Painter's Touch series .

Tamiya's rattle-can primer  , their Surface Primer , is great but it went from expensive to super expensive lately .

The above contain solvents that create a stronger bond to the polystyrene . ( butyl acetate , butanone , acetone etc )

For airbrush application I would avoid the true water base acrylics for primer due to low adhesion .

Badger's Stynylrez Primer is a polyurethane and performs well on plastic . I believe Vallejo also has a polyurethane primer for airbrush application .

Vallejo also has a rattle-can , solvent based acrylic primer similar to the Tamiya formula that is cheaper by volume .