[Mr Hardware]

Yeah, at least 13.x volts if not 14.x is the normal range for a working alt.
Just check your alternator, the power steer pump sits almost directly above the alt in an I6 and sometimes can stop working due to it being covered in fluid.
Alts are pretty cheap from memory, just get one from bursons or some such, and not too difficult to change, i think there's a writeup on here somewhere. Loosen the belt, a couple of bolts, a couple of cables and robert's ya father's brother.