We have a Sunoco down here that sells 110 leaded right at the pumps. It is used by the air boats that run through the everglades. Popular with the gearheads too.
By comparison it is cheap these days @ $5.25 gal.
the price has been the same for years.
I mix 1/2 *110 & 1/2 *93, and my engines are very happy.
I don't know if there is a difference, buy i try to use Mobil or Shell, had a bad knocking experience at a BP/Amoco. Had only used them, but the quality seemed to lag.
Loads of places to get AV100 low lead, but I don't really like it. I had also heard that AV fuel was not good for the cars.