[s-cars] serpentine belt tensioner

[JR]

Ok, my serpentine belt tensioner is going bad.  Not the bearing, but the
spring loaded part that creates the tension.  It's supposed to push the
roller down on the belt creating tension.  It does.  However, when I use
a crescent wrench to remove tension from the belt, I can pry it back
almost an inch without engaging the spring.  Meaning that there is about
an inch of play in the tensioning arm before encountering the spring. 
It is very sticky and doesn't move without effort, which is why it
hasn't failed altogether and stranded me somewhere, but the spring is
obviously not doing it's job and the whole thing is a ticking time bomb
waiting to go off.  Plus it squeals like a stuck pig making the whole
car sound like an old jalopy at stoplights.  I am not driving the car
right now.

My question is this:  Should I buy a new one for $180 from the stealer
or can I just get a used one for $80 from Force5 and replace the roller
bearing.  I already have a new bearing because I was going to replace
the roller bearing before the rest of it went bad.  Am I the one in a
million that has a failing spring or should I just bite the bullet and
go new?
Thanks,

JR