Good deal?

Good day everyone, i’m new here!

I’ve got a quick question. I recently paid €550 for a Base Set booster pack graded PSA 9 with the Blastoise artwork. It’s something I’ve always wanted to have, especially since Blastoise is one of my favorite Pokémon. I’m genuinely happy with the purchase, but I’m not 100% sure if I paid a fair price.

The seller (from a Pokémon convention) mentioned it weighs about 21.30 grams before grading, but I don’t have any proof of that. I see it as both a hobby piece and a potential investment that I’d like to hold for around 10 years.

I’ve seen similar packs on eBay priced between $550 and $700, so I’m curious to hear your thoughts and opinions on whether I got a good deal!

Thank you in advance :)!