Written transcripts of audio files from focus groups

Hi there - I have four 90 minute sessions that require transcription to the best of one's ability - I can supply DVDs too as back up as well as a script of the questions asked, and ohter support materials, to help with comprehension. I am uncertain as to how long these will take but I have been advised that 15 minutes takes one hour of transcription so if this is the case then we are looking at 24 hours of work - let me know if you think differently. I am happy to agree a fixed fee in advance if this suits you better. I look forward to hearing from you and please let me know your general location as being near to West London will help with transfer of the DVDs (though I can post them of course) and when you think you can deliver this work by if awarded the job. Thanks in advance for your interest.