Every teenager in my life loves the Garment District, which carries an amazing selection of inexpensive contemporary and vintage clothing, costumes, and accessories. Also amazing is the amount of effort sometimes required to unearth just the right item, which may be why you don’t see a lot of adults here. “By the pound” merchandise (actually $1.50 a pound; not available Fri) is on the first floor. Also on the premises, Boston Costume is the area’s best source of rental, retail, and vintage costumes, which are available year-round.