Depends on your lifestyle
We are planning the same escape and in my research it seems to really boil down to how you like to live and where you want to go. Some places are much cheaper than others.
If plan to not spend money eating at restaurants, hanging out in bars and anchoring out instead of hooking up to shore power then you can get by pretty cheaply maybe in the neighborhood of $800.00 to $1000.00 a month but is seems that more often it is closer to double that amount. This includes insurance, moorage fees and such. It doesn’t include major replacements of items such as sails or engines.
I am also hearing that the cost making landfall is getting out of hand…. Due to extortionate government rip-offs for "cruising fees" $150-$300 fee per boat for entry is becoming typical in many areas.
We do not currently have our boat yet so all my info is definitely second hand. We are on the "two year plan" and intend to start retirement at least semi retirement by 2010.