Inexpensive Christmas gift ideas for boyfriend who is in SCA? $20 limit, Greek reenactor, in military...?

Why don't you get or make a gift that concentrates on your relationship rather than his individual interests -- like a photo collage or framed photo of you both. At craft stores you can find key rings with locket type photo holders attached -- that would be nice too. And the schnapps idea you had was a very good one!