Is it normal to think of marriage?

I met my boyfriend when I was seventeen and he was eighteen. We've been close friends ever since, and have been in a long distance relationship for almost a year now. He's turning twenty this year. Soon, we're going to be living in the same town. We are a lot alike and understand the meaning of compromise in a relationship. I'm still much more childish than he is, and get distracted easily by other men but I know it's him I love. We understand each other and don't want to change each other. He's my best friend, my companion, and I'm his. We both don't want to get married, but lately I've been toying with the idea. When I found out that you have to pay the government to bind yourself legally, I was kind of horrified since I don't want to pay for an act of love. But I'd love to refer to him as my husband. So what do I do?