Currently I'm paying $4.01/gal for 91 Octane in AZ. I don't remember what it was last year but two years ago it was about the same. In the time between it dropped to $3.85ish (I think) and now went back up to $4. Refueled a few days ago, I believe the total price was $56, but my tank was not completely empty.
Thankfully Jet A is not really rising, $5.75/gal.