the guy took the time to sort out 8 horns for you that you didn't own. How hard is it to find 8 museum card doubles to send back to him? (i'm assuming you don't dupe) i would understand if he wanted a car or ticket, but he's asking you for museum cards which other people are taking the time out of their day to send to you for free.
If you have time to sit their and rake your inbox and check off your items in mygt, then you have time to sort out some museum cards for a new member who took the initiative to try and help you. People are sending you full sets of gear and just about every other item and your not willing to complete a trade for 8 measly museum cards because your so spoiled from the generosity of the members from this forum sending to you for free!
Anyway i'm not stopping you from doing what your doing, i never helped you in the first place and never will, so good luck and carry on...