I found it like an ICO listing websites with an upvote system, and I feel like it has existing script on sale on the internet but you have to edit some terms coz they're technically different, if you have a basic php programming knowledge I guess it would cost you less.
Gemspree.finance was done in WordPress CMS. I can't find which plugin is used here, but someone experienced probably can recognise or suggest plugins that can handle this function.
I will always suggest WP for people who are not familiar with any programming language. Platform
WordPress was constantly updated, also most of the popular plugins.
But hiring someone knows in web/php development would be much better than buying a script if you really don't know on how to build such website.
Hiring someone for such a small business, not the simplest. refinements and corrections are often required, and that sometimes requires more time and of course money. it seems to me that OP wants to do this as a hobby with the possibility of potential earnings.