Sad to say, the true value of your GL2 (I have one and know how GREAT a camera it is), what you originally paid for it, and what you will get from a company that purchases used equipment, or what you will be offered by folks who frequent ebay or Craigs List will prove miles apart. I came to that realization recently when attempting to get enough out of my two XL1 and one GL2 to purchase (I'd hoped) at least one Panasonic 150, maybe even a bit toward a second one. Nada.
I will wait until I can pay cash for the new HD production cameras and have decided to keep my Canons because they are worth MORE to me than they are to virtually anyone "out there" especially considering market value when compared to current technology.
So, mine will become backups, live feed tools, second gig cameras, perhaps even rentals or loaners to others who work for me from time-to-time. Pretty much ANY gig they will be used for will be as much, if not more, than I could get anyone to pay for them.
You will NOT get what that camera is really worth, trust me.