Typo:
> allowing to anyone to find trustworthy
should be allowing for anyone to find..
Also, I understand why you indicate your alma mater as 'one of the best' because most people outside Colombia likely won't know it, but you should still list what institution it is, simply because the vague-ness is a little discomforting.
Overall I think a simple Reddit-style moderation with votes can certainly do a lot to improve an experience like this, but reputation systems are very difficult. There are many ways to game/manipulate systems like this, starting with basic sybil attacks, but also coercion (e.g. show me your privates or I downvote you), and other imaginative abuses. It might be worth discussing moderation strategies beyond the voting system.
Finally, $1 a year payments sound like a lot of user friction for little benefit, and also payment processors are likely going to take a large fraction of that. It's a difficult choice, but some kind of 'freemium' model seems attractive here: a few dollars for high-quality emotes, etc. People that really use and enjoy a service tend to be quite open to payments like this, and it's a proven model for games, Twitch.tv, etc.