The Hangman's picture hanging services are charged at the same rate, regardless of size/weight and complexity. It's somewhat tricky to accurately assess the time required to hang a picture or mirror as there are many factors at play : wall surface, size/weight of picture, presence of hardware on picture etc.
As a basic guide, a large mirror can be prepared & hung within 30 minutes. A large, heavy mirror installation that requires hardware for both a 'hollow' gib wall and mirror, will consume roughly $32. A small, light-weight picture that requires hardware for both wall & picture, would cost $2.00 in hardware.