Business Research transcription

I am working on my dissertation and conducting interviews with 20-25 research participants. Each interview will be approximately between 45-60 minutes long. I need the interviews to be transcribed. I start data collection on July 21st, 2009, and the recordings will be available from august 3rd, 2009. Please tell me give me a quote for the charges for transcribing the interviews for me. since this is academic research, I am looking for someone who can do this for cheap and respects participant confidentiality.