I would ask the same.What exactly is the problem besides the age of it?Leaks? Alot would depend on any major structural damage.If your just trying to buy a couple more yrs and have no damage just do the cheapest fix.Personally I wouldnt even consider an entire new roof.It would cost more then what its worth.I had a buddy replace his entire roof,leaked after he was done.
Ive heard decent things about that roll on roofing.I believe its latex.Maybe check that out and get a young guy to roll it on for you.