My experience cruising the Eastern Fl coast is there’s fuel delivery companies up/down and prices are significantly lower than marinas
We used to do this when we could also.
Places to meet started getting harder to schedule.
Schedules were getting harder to keep, for the boat and truck.
The oil/fuel companies were getting complaints on 1 or 2 drips of fuel in the water (even when there was none).
Fuel prices mostly vary by convenience.
The closer they are to you, the more they charge.
Overall, fuel cost is not the biggest factor, Getting on/off the fuel dock seems paramount to me.
The cheapest diesel dock in Jax has a ripping river current and the fuel/dock folks really don't want to help. Lots of fenders, lines and crew ready with PFDs on.
A large marina with minimum wind/current is shallow, tight maneuvering, one boat at a time, only fuel pump around, surrounded by most of the cities other marinas, cost the most.
IMO, plan your convenience, not a few pennies a gallon.