This is a multiple suggestion in one example.
Glowing eyes, any color, glows like LED and Halo
Eyebrows in a separate category, for angry, one eyebrow up, happy, etc emoticon faces
Goatee, and other facial hair options
Gary's hairstyle. It's spiky and cool, would look great in many colors.
Also, an open hoodie would be nice. I'm currently using the Cool Jacket and a black Backpack to hide the back, to look like an open hoodie.
Idc what price tag you put up for these vanity items, they will surely sell a lot.
Oh, and put Majora's Mask on the Glasses tab or nobody is going to want to wear it.
While I'm thinking about it, a Sweet Scent and a Dig Ocarina would be really nice to have. I hate carrying around HM slaves. TM slaves aren't much better, since only certain Pokemon can do certain moves, so it becomes a burden having a half useless team.