The richest purchase may be buying back control over your own hours.

Of everything money can purchase, control over your own hours is the one that most changes a life. When you decide when you work, when you rest, and what you say yes to, nearly every other problem becomes more manageable. It is expensive, unglamorous, and rarely bought because it requires giving up other things.

Work out what your fixed costs would need to be for you to have real choice. That figure is worth knowing even if it takes years to reach.