Howdy roofer,
Most recent (from WWII) membrane and rubber roofing is generated in Europe
and when it fails is marketed in US for about another 15 to 20 years.  Its
the oil, baby....   All kinds of metal roofs are available and copper panels
in no more than 16" squares, I can e-mail you spec.'s.  40 years life.  EPDM
is never better than 7 to 10, unless ballasted or coated.  Modified are good
for 15.  Forget all the exotics.  My bet is still for built-up with gravel
ballast ( need a to specify kettle man).  I PM some roofs that are 75 years
plus.
As for rolled roof... Home Depot is your place of purchase.  Roofing is a
science, however, dominated by manufacturers in this country.  So what else
is new?  One other thing:  its not the field, its the perimeters and
penetrations that count.  Water finds the least level of resistance.  Its
all about drainage, baby....
Best,
Leland