Spanish Interview Translations: Quality Test

I am in search of a bilingual Spanish/English speaker to assist in transcribing and translating an extensive set of interviews, totalling 7 hours of running time. In your proposal, please advise me of a fixed rate per hour of video/audio translated and transcribed. I need to estimate costs in this manner. These interviews are part of a documentary/ethnographic project about an indigenous Andean community in Peru. The interviews need to be transcribed in both languages. I would prefer a native Spanish speaker, rather than someone who learned it as a second language, as these translations need to be as accurate as possible so that no discursive meaning is lost or changed. I can provide you with links to sample videos from the interviews so that you can get a better understanding of the content that needs to be translated. As some of these interviews are up to 40 min in length, I would like to proceed with this job in translating stages. In other words, I will send you a batch of videos to translate, you would return the transcripts and, assuming everything goes well, I would send you the next batch and we would proceed as such. We can arrange payment in instalments. If you are interested and capable of this job, please get in touch. Also let me know if you have any prior translating experience. As I am on a deadline for this project, responses will be given attention on a first come first serve basis. Thank you for your time and consideration. I look forward to your proposals!