I have all the shirts, though some are retired due to age and/or condition. (My 2017 shirt for some reason has a bunch of small holes in it, and I know I didn't get acid on it at work.)
I still have the old Otakon shoulder(?) bag. Though mine is unique because the zipper on it is upside down. I also have several of the early pins (One of the earliest ones - the one w/ the bunny girl that reminds me of the Daicon IV opening, is darker than I originally recall. Whether that's 'patina', age, or just how it originally looked I can't recall.), and the 3 postcards they put out when Otakon had