HiTek Sunglasses

Most face vanity costs you your hairstyle. This is one of the few pieces that does not, since it only draws over the eyes and leaves everything above the brow alone. That is the entire reason people wear it over the dozens of full masks the game hands out.

The unlock chain is long. The Cyborg has to move into town, which means Plantera is already down, and then the glasses need Martian Madness beaten on top of that. By the time you can walk into his shop and buy a pair you are near the end of the game, so treat them as a finishing touch on a late outfit rather than something to work toward.