I used to opperate on a $20 a month budget...
It wasn't carved in stone, but I stayed close for quite a while.
I let go this spring and remodeled my workbench, bought a new airbrush and 'invested' in automotive body materials. I let go of my zero growth concept for a bit as well and aquired several kits (6+) without getting rid of the same number (building, selling, giving away).
And yet with all that, I spent less than I did fooling around with RC cars for a few months.