I basically swapped my home for the yacht, avoiding capital gains. I own her outright so have no mortgage payments. This number can vary greatly depending on the age and condition of the yacht, how simple or exotic she is, and how handy one is at doing it oneself. A lot of this can be avoided if the budget is tight. I usually go home once every other year and use frequent flier miles earned from credit card purchases.
Charts are expensive.
The more you travel, the more you buy. The same goes for fuel. We are not afraid to use the iron spinnaker on passages, so probably spend more than the average cruiser on diesel. On the hook, we use a couple of gallons a day for the genset. The good news is that it usually costs a lot less when you leave the States, and when you are in remote islands, one tends to rise and set with the sun.