I don't mind sharing costs...but it varies a lot based upon your personal lifestyle as well as the boat itself...
Kinda like asking "How long is a piece of string ?"
Anchoring is free. There are some free docks available sprinkled occasionally all along the route (search free Loop docks...lots of info out there )
Marinas vary A LOT in quality and services. Costs for us have varied from $25 flat fee to $7.00 per foot a night plus $30 for 50 amp electric (Liberty Landing Marina in the heart of NYC next to Ellis Island) but has averaged about $2.50 per foot plus $15 for 50 amp electric .
We frequently cook/eat onboard.....have 3 burner propane cook top, propane oven, electric cook top, microwave, Magma propane BBQ grill and small propane camp stove (outside on aft deck only).
Apartment sized 12 volt/120 volt freezer refrigerator and an ice chest for beer/canned drinks.
Some boats are eating out nearly always so their costs are higher.
Our boat is a Kadey Krogen Manatee 36. Full displacement efficient hull. My burn is about 1.1 gallons per hour at 7 knots. 280 gallon tank.
Other true trawlers (Grand Banks, Monk, Defever) travel similar speeds of 7 to 10 and get 2.00 to 6.00 gals per hour.
Semidisplacement hulls that are capable of 10 to 13 knots are burning 6 to 12 gals per hour and Carver, Cruisers, Searays, Bayliners that can occasionally get speeds up to mid-teens (a LARGE PORTION of the Loop is speed/wake controlled so the "go fast" boats are often unable to exceed 6 to 7 knots anyway) may burn 15 to 35 gallons per hour.
So obviously fuel costs vary widely. That is why trawlers are such a common choice in Loop boats.
Have paid between $3.65 and nearly $8.00 a gallon (diesel is around $2.00 per liter in Canada)
Full oil/oil filter/fuel filter changes every 100 hours....figure 12 to 20 days, depending.
Impeller changes and other various maintenance items regularly. I occasionally hire a diver to scrub my bottom ( go ahead TexAgs...served this one up on a tee....don't disappoint me !) and check anodes and prop.
We have a 40 gallon black water tank - larger than most - so we can go longer than most between pump outs. Costs vary from free (rare) to $10 (common) up to $40 (remote Canadian areas)...figure every week to 10 days
Ice is expensive...and bags a shrinking in size !!! We try to get blocks but only occasionally available.
Rental cars for sightseeing.....we have seen TONS...St Augustine, Savannah,Charleston, Annapolis, West Point, NYC, Yorktown, Jekyll Island, St Simons Island, Hilton Head, Washington DC,.....variable costs..
This is not exhaustive but gives you a bit to weigh as to costs.....its ALWAYS more than it appears.
And keep this in mind regarding boats......"Everything on your boat is already broken...you just don't know it yet !"