There is a lot of buses from l'Aquila to Fonte Cerreto. You have to change in Camarda and take a minibus (you don't have to wait) to Fonte Cerreto, where a good trail ascends to Campo Imperatore (you can take the "funivia" if you don't want to walk).
"After the first glass, you see things as you wish they were. After the second, you see things as they are not. Finally, you see things as they really are, which is the most horrible thing in the world."
--Oscar Wilde on Absinthe