People tend to like non GH copies of games, since the 'red bar on the GH package throws off their collection'. I know, it doesn't make sense to me either, since I buy games to PLAY, but some must just like to stare at their wall of games.
To each their own...
But to answer the question, people prefer the non GH copies of games due to the above reason or whatever and they tend to go for more money.
I bought a copy myself for $13.98 last week, which I may crack open in a few minutes myself to try out. I kept wishing it were down to $10 locally, but anything under retail is fine for me as far as markdowns go as long as it's not like $47.99 or something on a $50 game.