If it was 96-98 it was likely base set. So I would look on eBay at base set Japanese Pokémon/ pocket monsters cards to get an idea of value. Holos are for the most part going to have the value, unless he was giving you promo packs. But that's probably unlikely. I'm actually just jumping back into the collecting, I've got some cards from that era and was pricing some of the more rare ones out. If you want to post some pictures to the thread or pm me a few, I can give you an idea of value based on condition, at least a range. You want to look at completed listing on eBay for a good idea. It's also helpful to know that just because a card is like new, doesn't mean it will be a PSA 9/10 score. A lot of the high end scoring is a lack fresh card, with perfect centering and no defects from the factory. I base my own collection off of a psa 8 ish score if I didn't pull it and grade it.