Audio to text transcription

We are inquiring about audio transcription. We are looking to transcribe a series of phone calls for now 10 sales phone calls with two speakers each about 15 minutes long. That is about 150 minutes of audio needed to be transcribed. We are looking for a speed of about 40cents per minute of audio. Also the confidentiality of our calls is very important. Must be willing to fill out a confidentiality waiver essentially stating you will not share the audio files, you will delete them after transcription and not relay information contained in the files. I would attach the confidentiality waiver and have you email it back to me before we begin work.

Please Advise,
Lauren