I don't know what your margins are, but based on the merchandise currently in your store and the offer for my items they are very high. 
I realize you are a business and I totally respect that fact.

The offer I received was insulting. Perhaps this is standard business and a way to take advantage of young people bringing things in. 

After looking around the store while I waited and looking at the current merchandise pricing - you are purchasing items from people for just a few bucks and reselling for 4 to 7 times that amount. 
There were two items of mine that were not "accepted" and I believe the reason that was on the slip was 'wear'. Both items were brand new with tags (one being a brand new pair of Adidas sneakers that were $140). Seems a bit ridiculous. 
I realize everyone has to make money and that is what business is about - but I will not be selling or shopping here in the future. 
I think your store would thoroughly benefit from taking some pointers from the CT locations which are all run totally different.