Well, thats another advatage for me, I'm *maybe* the only one in a 100km radius that does these things. I was thinking about roughly 50 dollars, so i've got it confirmed, and i'll see what the feedbak is from the customers. And thank you all replies, on topic and otherwise

I just don't print the nessus scan, I also tell them they're in  deep shit and should probably hire someone to fix it *pointing at self*, should I charge extra for that?

Sadly, I see situations similar to what Kev mentioned all the time.  One of our new clients was a victim of this for about 3 years in a row. Gave the work to a VERY large company, and at the end of the year the results looked oddly like nessus scans copy and pasted into a different format.  Last year they tore up the contract an moved over to us.  Even within the same company it can really vary by office.  We just had an office in another midwest state piss off one of their large customers because they did something along these lines.  They had just started a new project for someone else and it was tying up all of their best testers.  The management thought they could get away with sending "the B team" over to the old client, kicking off some scans, and then tap dance through the rest.  Our relationship with the customer now resembles a smoking hole in the ground.  The managers still planned on sending over the "real" testers before the end of the project to do some good work, but they didn't get the chance as it blew up in their faces before then.  Anyway, morale of the story is that your can make your career and reputation by coming in after one of these situations and helping the customer get real value.  You get to play the white night.

As long as Nessus is on your list of approved tools and they signed the letter of authorization you are fairly safe.  We always give an overview of how we configure each of our tools and the possible impact in an effort to educate the customer before they agree to the testing, but you can't predict every possible risk.  For example, I was doing pen testing on a state government client early last year, and about 2 in the morning the target I was hitting became unresponsive.  I called my emergency point of contact who called the system owner.  The next morning we were getting our assess chewed out for being "reckless", and the system owner said we had done permanent damage to the box.  We found out later that day that the fans in the server had stopped working about a week before, and we just happened to be touching it when if finally melted down.  The system owner was trying to cover his butt by blaming it on us.  We didn't get an apology, but they also didn't question our testing methods anymore.