Hello,
My name is Sam and i'm a music producer, also specialised in sound restoration, with 7 years of experience.
I work in my own studio with professional equipment and softwares, like Izotope rx4, Zynaptiq, waves and similar, which are the top for what concern sound restoration.
I have to be honest, there's no magic in this field. In some points the voices are very, very low with a lot of background noise. The quality can increase but not so much. For example, extreme denoising can afflict the voice and make it less audible. The result can be bad to hear, but the voice can become more understandable in some points.
Skills play a relative role here, and also the most advanced softwares have their limits, this is why it is not reasonable to ask more than 70-80$ for this kind of job.
If interested, i can send you gratis a sample of your processed file. If you think it can work, then i'll proceed with the rest.
Please contact me if interested,
Sam