Quote:

EVERY primer will shrink. Which is why most high end restoration shops will let a vehicle sit in the final coat of primer for at least 30 days before they do the final sand and paint. This allows all of the shrinking to take place before final sanding.



That is exactly right! It's all about the prep, and that means what is under the primer. Personally, I use all PPG products with very good results. No, it is not cheap. But it hasn't failed me in the past twenty years, either.
If you had asked about the cheapest primer on the market, I would probably say use the brand most have suggested here. But you didn't.