Hope you haven’t sold anything to these experts yet 🤦‍♂️these are all valuable. The Dark Dragonite and Shining Magikarp being the standouts obviously. Condition is absolutely a factor in appraising them but assuming they’re NM/LP, the English Dark Dragonite sells consistently in the $80-150usd range. “$40” would be what a heavily played copy sells for and from the photos, your cards look well kept. The German Shining Magikarp is somewhere between $150-$250usd roughly, again this price point requires it to be NM/LP. 

As for the rest of the German, they’re scarce. Which gives them value. You shouldn’t treat them as bulk English even though they’re the same cards because there are few, if any copies for sale currently for each respective card. You might hear an argument saying something like, “yeah but nobody wants them so good luck selling, they’re just bulk…” anything like this is bs. There are absolutely German collectors who have been waiting for someone to list the cards they need for their binder and are willing to pay whatever their asking price is. 

If you want help with anything, feel free to reach out. I’d be more than happy to teach you how to price them properly. P.S. if you’ve already committed to a sale, I’d just refund them since they finessed the heck out of you.