Cheap and banshee don't belong in the same sentence...
It can be done, don't waste your time if you're that tight on money. It's all about the prep work, which costs money...and a good quality paint, which costs money...
Plus...sooner or later it's gonna chip off.
If you want to go ultra cheapo route, wet sand the plastics with 500 then 800 grit, primer them, then paint 'em.
And it'll look ok until someone drops a tool on it, you rub a brush, or you do anything pretty much else to it, including a good pressure wash....
People pay 300 to 2K for a good paint job for a reason, and even then it will chip off if hit/dinged/scratched.