If you want to know how much it costs to grade cards, or if it is worthwhile investment, all your answers about Pokemon slabs can be found here
To the question, I feel like some of these "defensive cards"/"control signals" are cards that this community has by and large shied away from for quite a while
If, for some reason, you're looking at a Pokmon card to buy, but you can't physically hold and inspect the card for yourself (for example, if there's a global pandemic, the shops are shut, and you can't go within two metres of another person), always ask the seller to take an original, high quality photo of both sides of the card for you
$279.99 Save $60.44 Chaos Rising has already seen its Booster Display Box tumble through several price points, but Amazon has now made it so you can grab the expansions biggest sealed product for under $220, while stocks last
Zapdos #27 Pokemon Japanese Crimson Haze Keep track of your collection value over time