thoughts on promise rings for men/ suggestion?

I really love my boyfriend, I really feel like he's the one. We act like best friends and I'd do anything for him. In late  February we will be together for a year. I'm really thinking about getting him a promise ring. I want him to know I'm serious about the relationship and I'm not going anywhere if he gets stationed in the military. Is getting a promise ring for men weird? Does anyone know what are some good quality affordable rings? I don't want to spend $100+ because I'd like it to some day be replaced with a wedding ring, but good enough to where it won't tarnish or turn skin green. He's never worn rings before, and he isn't a watch type of guy. He's pretty nerdy so I've been looking at "gamer" themed rings. Suggestions? Also any other suggestions that aren't rings but have sentimental meaning like a promise ring? I'm wanting to put it in a box and hide it in a room and him play "hot and cold" trying to find it.