yes, certainly the duration is to be considered when choosing the price.. I don't think that a 100 hour game has more value than a 5 hour one just because it lasts longer,
however the longer it lasts probably the longer it took to develop, if find the key had lasted 10 minutes instead of almost an hour, it would have taken me a lot less time to do.. by no means does that mean that just because it lasts 1 hour it's worth more.
people also consider this:
if I spend x on something that entertains me 100 hours, it's better than if I spend it on something that only entertains me 10 minutes.. so probably for the same price they will choose the game that entertains them more time, but in reality the game that lasts less could be a much better experience.
i am not interested in 100 hour games..just thinking about it that i have to play 100 hours to finish it scares me..it means at least a year to me,for the type of gamer i am a 2-5 hour game is ok for me ,
the only games i finished in one sitting are layers of fear and RE3 remake, or i remember with resident evil 2 on ps1 as a boy, i used to invite my school friends and in one afternoon we would finish it etc
the value of a game is not in its duration, but in the intensity / quality.. but yes, people consider the duration as a purchase parameter :)