Spraying a bumper

[Bananalad]

I want to get this bumper i have sprayed on the cheap i also want a good finish

Now i have plastic primer in a rattle can and i also have hi build primer in a rattle can already.. Do you think i could get a decent finish if i primed out of the cans and then just buy a half liter of water based colour and spray it out of a spray gun.. Same with lacquer.

I'm just thinking the primer will be flattened down anyway so it doesn't matter how its applied? Thanks for any help