How does baseball card grading compare between PSA and GMA?

Answer 1

Either way you pay for someone to fill out a checklist with some degree of subjectivity, and add up the checks to get a score. You can pay $17/card for the "established" PSA, or $2 for a newer GMA.

By the way, there's a rumor that someone can tell GMA what to grade to use. Someone is not reading closely enough - this is simply not true. GMA will act as a service provider to an independent grading company by encasing cards with that company's grade/logo. But if the card bares the GMA logo, it is independently graded.