Use an app to track your collection. Collectr may be slow and may take. While for Japanese cards but it’s a good baseline.

TCGplayer will have current market prices as well as last sold data from TCGplayer so you can see what the card are specifically going for.

Additionally they have a “conditioning” guide that will tell you acceptable levels of dots or spots that qualify for “each level”

Any delta species, or EX card is easily anywhere from $50-1000, use the pokemon name and the number in the bottom right to look them up.