Hip hop dancers wear pants that are loose and baggy and are usually in a dark color. Look through your pants and choose larger ones that you may not wear because they are too big. A pair of cargo pants would work well. If you don't have a pair, check out a local thrift store. Buy them in a size too large. The pants should fit low on your hips. You may decide to wear jeans, but if you do, make sure they are baggy so that you can easily move while wearing them.
You can use some things from around the house to take regular tops and make them into to hip hop tops for cheap. If you have over-sized, white T-shirts, use fabric paint to paint bright graphics on it. You can also purchase an entire package of large, white T-shirts from the store for about $12. Graffiti-style graphic T-shirts are perfect. Choose a T-shirt of a contrasting color from your pants so that your dance moves can be clearly seen from both the top and the bottom of your body.
Accessories to your outfit will drive home the image of a hip hop dancer. Begin with a large chain. Most hip hop dancers prefer gold chains, but you can purchase a cheap, silver one and spray paint it gold to make it look more authentic. Also make sure you have a fitted cap. You can find plenty of caps at the thrift store. Purchase one and flatten the brim; hip hop dancers don't wear it curved. Finally, use tin foil to create a grille for your mouth. Fold it into strips and mold it to your teeth for an authentic hip hop look.