One mans machine polish will vary greatly from the next. Its nigh on impossible to quote a flat fee without seeing the car and inspecting whats actually required.

You could be looking at a couple of days work if it needs plenty of work, conversly you could find someone "in the trade" who'll "mopp" it for £50!!!

I used to refuse to give quotes over the phone when i had my own valeting business because you could trip yourself up very easily (financially i mean).

As a rough guide, if the car needs claying, following by a good correction with the rotary, then protecting with sealants/waxes, you could be looking at £200 + very easily.