Graded baseball cards trade in a different market from the same cards raw. The slab settles the argument about condition, gives the card a certification number anybody can check, and makes it shippable without a conversation. All of that has a price, and whether the price is worth paying is arithmetic rather than opinion.
What the grade actually does
A raw card's condition is a matter of opinion between a buyer and a seller who cannot hold it. A graded card's condition is a number assigned by a third party and sealed with the card, so the buyer is no longer taking the seller's word for the thing that decides most of the price. That is the whole economic function of the slab, and it is why graded prices are usually tighter than raw prices for the same card.
The step between grades is not smooth
People assume a ladder where each grade is worth a bit more than the one below. In practice the steps are irregular and the top one or two can be most of the price, while the middle of the ladder is close together. That means the grade you actually get matters enormously, and it is why costing a submission against a hoped-for top grade is the classic way to lose money on one.
Compare graded to graded, at the same grade
When you read completed sales, a graded card at one grade and the same card at the grade below are separate markets, and both are separate from the raw card. Filter accordingly. A price you found for a high-graded example tells you nothing about what yours will fetch unless yours comes back at the same number.
Then do the subtraction
The grading uplift calculator sets the graded price against the raw price and the all-in cost per card, both after the marketplace's percentage, and gives you the net gain and the graded price you would need just to break even. For most ordinary cards that break-even is higher than the card is worth in any grade, and the calculator says so plainly.
Questions people ask about graded baseball cards
Do graded cards always sell for more?
No. They sell for more when the grade is high enough to matter and the card is worth enough for the certainty to be worth paying for. A low grade on a common card can sell for less than the same card raw, after you have paid to put it in the slab.
Can I sell a graded card more easily?
Usually, yes, and that is part of what you are buying. A buyer who can see a grade and verify a certification number has fewer reasons to hesitate, which shows up as a faster sale more often than as a higher price.
What if I disagree with the grade?
Graders offer review and reconsideration services at additional cost, and the original fee is not refunded. Budget for the first answer being the answer.
Should I crack a slab open?
Removing a card from its holder throws away the certainty you paid for, and the card is raw again the moment you do. There are reasons people do it, and none of them are about value.