Sure, Home Depot/Lowes/Ace Hardware

All you need is either a number of washers or a cut to fit bushing like piece of solid metal, and probably some longer bolts.

I understand a dealer not wanting the liability, but this should be a pretty easily overcome distance, I've heard and read of a number of people lowering or raising the seats in the S.

As an aside....my wife is 5'1" as well and while she has basically refuses to drive my car, she was able to just fine when she tried just by the seat adjustments so I can't see your wife being too far off from comfortable with just a little adjustment.

Travis