I'll go first: Ken's Special. Any longtime Bozeman resident (or smart newbie) would know exactly where I was talking about. That's not even my fave item on their menu but it's probably their most well known.
Most of my favorite things to spend $10 on involve food, but that's just me. But if you need to be a little frugal but also need a little pick-me-up, Bozeman does have some good options for about $10.
I don't care what that says about me. But when my world isn't right, there is no person or thing that makes me feel better than a Pickle Barrel sandwich. No joke.