Thrift stores are wonderful; I love 'em.

I feel very conspicuous in a T-shirt, and they are not flattering: the fabric, if tucked in, reveals all the bumps I'd rather conceal; if left loose, hangs straight down from the furthest promontory, making me appear somewhat like a two legged tree trunk with a head on top. A buttoned, darted shirt narrows in the right places, can be unbuttoned as far down as one likes for comfort or discreet display (hey, cleavage is one of my few assets!), and is available in a variety of fabrics.