Sounds like a plan... Not much experience with a megger though. Costly, I bet they are, you have a figure I could go off of?
No way can I give you a number. I don't know what all you're up against. But at least you'll be able to get some well-paying work if they bite at your offer.
You could give them a price to meg & test everything, then it would be T&M if you find anything that needs attention.