Stylish yet affordable. No matter how often you hear the phrase, you never tire of it. W hotels? Jet Blue? Lavande spas? Bring on the reasonably priced cuteness! Okay, then: Bring on Mercer Street, a new hair salon that caters to those in need of great haircuts at reasonable prices. Step into the bright, attitude-free space on the corner of Fillmore and Union and pause to take it all in: the stylish Danish-modern decor, the stenciled yellow walls, the black-and-white furniture, the yellow Lucite details, the ’70s light fixtures, the friendly faces … Then marvel at the service. Mind you, stylists from all sorts of fancy salons clamored for a gig here, but only the truly down-to-earth and pleasant made the cut. No prima donnas. No François froufrou. And for a mere $55, you can get a haircut, head massage, blowout, and a Sibby’s cupcake. Highlights are $95 for partial and $125 for full. Why do all this for you? Guess they think you’re worth it. Shouldn’t you? Mercer Street, 3012 Fillmore Street, at Union Street (415-674-4444).