I'm not sure I should even go for the achv now because there are 15k items in there. I bought one out and tried to sell him a dusk ontra trading card, but he wouldn't accept it.

He doesn't accept r99s, but it gives you the achievement anyway. :) It looks like you have it!

oh god, I apologize, I was looking at my achievements. xD Um, the same thing happened to me, but I still got the achievement? Perhaps you should try again.

he takes [item2=All Seeing All Knowing Crystal Ball of Terriers]

Thanks! He accepted it :)