The Pep Boys are correct. I had the same "Christmas lights" come on the dash while driving and it was the alternator.
A brand new alternator for my 2001 base was $1,400 from a dealer.
I paid about $170 for a refurbished part from Autozone that came with a lifetime replacement policy. I am pretty sure Pep Boys has similar policy.
Replacing the alternator can be a DIY if you are inclined and have the tools.
I say get your hands dirty.
