I have sold two cameras and some lenses to Adorama. I made the mistake of sending them several items at one time.
They told me they didn't "want" some of the items, and yet offered me $1,000 for all of them. I had given them a list of everything before sending them my items, and they said they wanted all of it, and offered a estimate of $1,900 to $2,100.
I held them to their word about sending the items back, and they started to act reluctant, and got some managers. Finally they quoted me a price on each individual item, and I accepted three of their prices (D90 for $450, 50mm f/1.4 for $175, etc., all in mint condition). They really did a good job of making me think that these were the best prices I could get, about $25 under what they could re-sell them for. (Ridiculous! I think I saw my exact same D90 on sale at their website for $800 the next day). They did send me back one camera and one lens.
I ended up getting $950 for about two-thirds of my stuff, but I could have received at least $500 more on Craigslist. That was before I had tried Craigslist.
I have since sold an equivalent lens for $100 more, an equivalent camera body for $250 more, etc.
I would never use Adorama again to sell my used equipment to.
Regardless of where you sell your used equipment, to be successful, you must be willing to give the buyer a good bargain. I see so many posts on the bulletin boards of big companies of people trying to sell their cars, cameras, etc., for MORE than what they paid for them long before. That's goofy. Even if I have something brand new to sell, if I changed my mind for example, I still take off at least 10% from what I paid just as the "price" of my own stupidity for buying something I didn't need, and a courtesy to the purchaser, no matter how good of a deal I got originally.