"Be Nice or Go Away" reads the sign above the cash register at Poor Little Rich Girl in Somerville. And that’s pretty much the awesomely independent, help-me-help-you attitude exuded by Meredith Byam Miller and her consignment shop. Formerly tucked away in a 650-foot hole-in-the-wall closet along Highland Avenue in Davis Square, Byam Miller’s small business recently relocated to a 4750-foot expansive storefront around the corner, beside the Burren, where the West Coast Video chain store used to be.

That means, among other things, that West Coast’s legendary backroom of porn films has vanished, having since been gutted and repurposed for shoe racks and baby-carriage-friendly dressing rooms. (Since the move in September, Byam Miller has watched many a lone man unconsciously walk into the store and become visibly horrified to find Pumas in place of The DaVinci Load.) It also means that Davis Square, a neighborhood whose character is slowly being homogenized, given the loss of the Someday Café and rumors that a CVS and a gym are moving in, might not become totally lame.

Poor Little Rich Girl opened nearly five years ago. For the four years before that, Byam Miller, who’d majored in fashion design, managed the consignment shop Second Time Around in Harvard Square. “I never thought, ‘I’ll open a store.’ That seemed so ridiculous to me and out of reach,” she recalls. But over time, she learned that running a secondhand store wasn’t all that hard. “Then I realized, I’m not a great employee, and if I’m gonna do something, I’m gonna do it for myself.” And so the store was born.

Poor Little Rich Girl is not only the name of a 1936 Shirley Temple movie, it’s also the title of a 1965 Andy Warhol film in which Edie Sedgwick lazes around, talks on the phone, smokes cigarettes, and tries on clothes. It’s the latter film that inspired the store’s name. “I thought, it fit what shopping here meant: you’re poor but you like good stuff,” says Miller.

Stuff like, say, a hip-looking second-hand ski jacket priced at $24. Or a pair of Dolce & Gabbana striped heels marked down to $125. Or a pinkish-orange hand-knitted winter hat for $14. And even though the business name is gender-specific, Miller keeps a few racks of men’s things.

Back in the late ’90s and early 2000s, Miller was one-third of Heavy Stud, a power-pop trio who baptized the Abbey Lounge by playing the Somerville bar the day it opened, and whose songs were featured on Dawson’s Creek. Miller’s new project is the primary reason Heavy Stud hasn’t played together in a while: she hasn’t had a day off in two months.

Still, her rock-star past ensures two things: good shopping music, for one. “I hate walking into a store and hearing crappy music,” she says as London calls the Clash from the overhead speakers. It also speaks to the fact that she knows what it’s like to be low on funds: her prices are ridiculously fair. “Sure, I want to make money, but I don’t want people to be like, ‘What are you talking about?’ I don’t want them to feel raped.”

Poor Little Rich Girl, 255 Elm Street, Somerville is open from Monday through Thursday, 11 am to 7 pm; Friday and Saturday, 11 am to 9 pm; and Sunday, noon to 6 pm | poorlittlerichgirlstore.com | 617.684.0157.