As a child I had considerably more than 42 Pokemon cards, from that time range, and all in excellent condition with several "shinies"... all of which went into the washing machine because I left them in my pocket. Depressing.
I had at least that many, first generation as well, including a bunch of Japanese shinies that my mum found in a shop somewhere and bought for me.
They all went into the loft at some point and later ended up in a bonfire along with my first edition Harry Potter book collection when my mum was doing a "clear out". Such is life.
Just to clarify: it was 42 _sets_ of cards, not just 42 cards.
Eh don't beat yourself up. Value for these sorts of things are extremely condition dependent, if you were playing with them then they would already not be in the condition to fetch these kinds of price.
The fact people did this sort of thing by accident is why the cards he had were valuable. If everyone who had cards as a kid still had them no ones would be worth very much.