7 Continents - 75+ countries - 1000 days - NO PLANES

I'm trying to figure out how much I need to save to spend three years on vacation? I do not like to fly. I want to circle the globe and I want to take my time in each place I visit. I also want to do it as cheaply as possible. I will try to make my own food and camp wherever possible. In big cities I am going to attempt to rent an apartment for a month at a time. Then move on to the next city. In some countries, joining an organized tour group will be my preference. This trip starts in Iceland because I have been unable to find a way to Iceland without having to fly. I live in California and would likely be driving my car across the continent and selling it on the east coast. Then flying to Iceland to start my trip and never fly again.