You don't have to pay hundreds of dollars for punk clothes, which usually look as if they've gone through the wringer anyway. Just take a few of the clothes you already own and run them through the wringer, or at least jazz them up a bit. Punk clothes should be ragged and ripped. You can make your own punk clothes with some basic supplies and a few fashionable steps.
Start with T-shirts. Just about any T-shirt can be turned into a punk T-shirt with a pair of scissors. Cut off the arms just below the arm hole seams. Snip away the neck hole just below the neck hole seam. Cut the border off the bottom. You can even cut some length off the bottom if you want your punk T-shirt cropped. Wear the tee by itself or over a ruddy tank top or long sleeved long john shirt.
Fashion a skirt. Take a swath of material, scarf or tablecloth with an eye-catching pattern. Place one corner of the cloth at your hip while you wrap the rest of the cloth around your waist. Keep wrapping until the cloth runs out and secure the other end of the cloth with a safety pin at the hip. For a shorter skirt, fold the fabric lengthwise or cut it before you wrap. Wear with fishnet stockings and combat boots.
Do up blue jeans. Run a pair of blue jeans through a dye bath, whitewash or both. Snip off the hems so the bottoms fray. Stitch or fasten several chains around the belt loops so the chain hangs down in graceful cascades. Sew on some silly patches with funny sayings, such as "Don't eat yellow snow." Couple the jeans with one of your tees and high-top canvas sneakers.
Jazz up a jacket or vest. Get some snap-on studs from a craft store and line them along the neck and front of the garment. Put some spiked studs along the shoulder seams. If the jacket or vest looks too new, throw it through a whitewash bath before you stud it up. If your vest or jacket is leather, you can also secure a sticker to the back with heavy duty washable glue.
Modify the vintage. Take any vintage or thrift store clothing item and run it, too, through a dye bath or white wash. Form-fitting 1950s dresses, an old suit jacket or lace skirts that reach to your ankles are all great options. Heck, those are all great options you can wear at the same time. The vintage stuff looks best if you crumple it, ball it up or randomly wrap rubber bands around it before dying. This way the dye comes out uneven and really punk looking.
Dye and whitewash are available at fabric stores, craft stores and even in most supermarkets. You can also buy online; see Resources below. Studs, safety pins, patches and all that jazz are usually rife in fabric and craft stores. Enhance your selection even further by seeing Resources below. Garage sales are another great place to get cheap clothes to punk-ify. Size doesn't really matter when you're going for punk clothes. Big and sloppy is a great punk look. You can also do makeshift tailoring by pinching fabric and securing with a row of safety pins.
Make sure your punk clothing is complimented by a punky hairstyle, like spiked or shaved. It will look stupid if you wear this stuff with strait-laced hair. Don't try any of this on brand new clothing your mom just bought you for school. If you do, you'll never have a weekend throughout the school year that you are not grounded.