Very niche email database worth?

Hello,
I have collected over 18,000 emails account through my small business. We are located in an attraction park where we take pictures of visitors(mostly tourists) while they are doing attractions & tours and sell them the pictures digitally and they download the pictures through a cloud sharing server. We explicitly tell them that they need to give their real email address so that they can download it. I have started collecting the emails from Feb 2018 to this date (70% Europe, 20% Asia and 10% local people). I was looking to sell the database to one of those company that do in demand print or photobook. As far as i can tell, they are high income people and around 60% female & 40% male. How much does it worth? I read many things online, some says nothing and some says a lot of money. And many has told me that i would get problem because of GDPR laws. But i am not in EU for the record. I don't have time and resources to built something around it. But i would appreciate some advice. Thanks.

it depends on the quality, obviously but if theyre all active and you clean the list often maybe $2500, rough estimate but should provide some insight