So much depends upon one's expectations. I have been told that the best bordellos in the world are in Madagascar off Africa and Manaus along the Amazon River. Any island landfall is always of interest after a month at sea, however, the south coast of Alaska has some of the most awesome scenery while the tides of up to twenty feet and currents of eight to ten knots keep one alert. Salmon, shrimp, crabs, halibut, venison, etc keep one's appetite sated. My personal favourite is what is called the Pacific Gyre or the high. As the winds and currents go clockwise in the North Pacific from Japan to Alaska to California to Hawaii and back to Japan, the centre has no wind. Thousand miles from the worries of living on dirt. Best vacation ever.
The ease with which you can use the internet to find a boat anywhere in the world masks the costs of travel to find, purchase and modify the sailboat. These costs do not add value to the boat, but they increase the cost of the boat.
Finding the Boat
Unless you plan to buy the boat sight unseen, you will have to travel to the boat. Further, you have to plan to see more than one boat; after all, how likely is it that you will want to decide on one boat without seeing other boats on the market? Personally, sailboats for sale in sailing centres like Annapolis, MD and the Chesapeake Bay, Miami, San Diego and the like on the US coasts are some of the best places to find sailboats. Personally, I recommend Annapolis as one the cheapest. I caveat that because I live here but because in terms of sailboat density, the Annapolis area is one of the densest in the world. People come here from other places to buy boats. Especially from Florida after a storm. Every few years, a place in Florida gets their inventory of available boats wiped out by a hurricane.
In general, boat pricing is better in larger markets than smaller markets. Sailboat markets, however, are concentrated. Yacht world shows 13,800 used sailboats in the 35 to 55 foot range for sale worldwide as of December 2017. Of these, 4300 are in North America, 95% of those are in the US, 60% along the eastern seaboard alone; 8,000 are in Europe and 75% of those are in the Med