I am a firm believer that if you want to have a costume of something you don't have to make everything yourself. Often times you can find what you need at a better cost to you (when factoring in time and money).
Black Canary in the DC universe tends to have a pretty classic look. Her Justice League Unlimited (JLU) tv show version is not a big departure from her comics design.
I wrote a tutorial putting this entire costume together for Halloween Costume Supercenter. If you are looking for a quick costume of a badass lady this one will definitely fill your needs. You can see the full tutorial here.