How rare are these??

They were re-printed in English so not that valuable.

The amount of English cards affect the worth of Japanese cards?
I have seen plenty of cards that are almost worthless in English but quite valuable in Japanese, so this concept is new to me.

Sometimes it does affect the value because the artwork becomes less exclusive. It also gives the illusion of the card being less rare. Good examples are PLAY Vaporeon, Jolteon and Flareon. All three diminished in value with the English releases.

Card values work in funny ways sometimes, it’s not always pure rarity.

Hmm, that makes sense.
The English font for the names is so ugly though!
I was on eBay looking for prices for Surfing Pikachu and I saw the English version.
Before that, I never knew it was actually called Surfing Pikachu in English.
I’d never buy the English one.
Plus, English cards always feel less exclusive to me.
Is it true that English cards are printed in way higher numbers?
I’ve seen stacks of hundreds (actually 3600 in total) of mew cards, you know, the non-holo boring one.
Never seen this happen with Japanese ones.

Well as the one pictured is the DPt-P version that makes it quite rare because there weren’t many printed before the change over to the L-P print were alot more of these were printed which usually are priced at around $20 or a bit more.

Iv personally sold 2 DPt-P versions one for $120 and another for $150.

alot of japanese rare promos will go down drastically in value after the english sets comes out or is mass produced sadly.hence why collecting the rarer promos are worth it since some have never entered the western side

The card is worth significantly less compared to what it was worth before it was re-printed. The same goes for the Great Raichu promo. Any card that is re-printed in english drastically changes in value. A lot of collectors do not bother with a japanese card unless they are only printed in japanese.

If you check the most valuable japanese promo’s they are typically a card where the illustration was not re-printed. The Fan club Eevee is a great example. The card was re-printed in english with a different illustration. Since the original fan club illustration was not re-printed the card still maintains its value. A re-print of an illustration always decreases the value.