If we're talking just the Core Rulebook's spells, and no failed Knowledge (arcana) checks, then you're looking at nearly 34 years and an expenditure of over 175,000gp.
It's no wonder wizards are all looking for immortality and wealth. ;)
by which method of research?
With or without bathroom breaks?
Using the method as presented in the Downtime Rules for spell research in Ultimate Campaign.
Is there more than one method?
Pretty sure these time estimates allow for breaks to eat, sleep, and go to the bathroom, but not much else and generally represent your common 8-hour working day.
there's also the separate and completely differently costed rules in the GMG here