For me it's at least £10k which was approx 15% of my income at the time.
Cost of fuel, tolls, parking, buying lunch because I needed to escape the office, random purchases because I have no control, dog sitter / walker - actual costs I could quantify.
Unquantifiable benefits - my chronic migraine is under control because I can manage my environment (heat, light, sounds, smells), increased time spent with the dog who is aging, increased time spent with the husband who deploys for months at a time, flexibility to do local things like pop to a GP appt which takes me 45mins but would have required a half day off in my old job. My mental health is the best it's ever been.
Sticking on a wash, turning on the dishwasher, running the robot hoover and bring able to rescue it, accepting parcels at the door.
Avoiding office politics, not wanting to murder people for eating with their mouths open - priceless.
However it's probably come at a cost to my career trajectory, so that's worth considering in advance.