Anyone know the cost to get an RV rubber roof replaced?

I asked for just a ball park number from our RV guy. Here is what he told me, if I remember right about 4 years ago.
$100.00 every running foot and add $100.00 for every opening, no matter how big or small (vents,frig, skylights etc). And what ever that number is add $700.00 and that is at their shop and without a deadline. Think I remembered it right. When I added it up, I decided I'll wait. I see prices on this forum that are way out of line or maybe only RV dealer around for miles. The scary part is what are they going to find underneath?