First of all, $80 for "gaskets" is nuts. Of course if you have to replace the pushers then the $80 price isn't off by too much. I'm thinking $640 is still a bit high. I'm guessing you'd pay around this much for a full restoration in Bienne and at least it would be done correctly.
Is this a well established watch service? Did they disassemble the movement already to give you such a detailed and precise quote? Sounds like they must have to know exactly what parts need replacing.
Personally, I'd get a second estimate.
Chris