Originally Posted by serfty

stan1162 , eznh has provided some good points.

For such as this you need to know where to start. In most cases a DONE4 gives better bang for your buck - but that is somewhat dependent on where you actually want to go/see. For now, lets look at the costs of this OneWorld Explorer four continent fare which varies in base cost depending on the country of origin.

Starting in the USA has a base cost of USD12.2K, Canada USD10.5K per person. If you can fly to Oslo and start there the base cost is USD5.1K. Or Japan at USD6K (It can be useful to start outside the continent of residence - this can be wangled to give a breather mid trip.) See here for contemporary base price examples:

https://www.flyertalk.com/forum/36757225-post2617.html

It is not unreasonable to expect to be able to comfortably locate oneself to a start point for a price point much less than the fare difference in the cost of starting in North America.