Once an old jewish character, Haantje, he was called, who lived in a shoe box before picking up and heading out to Bulgaria where he lived in a mud hut, told me something credited to this Isaiah figure: Something like this, "Before building your house, make your best guess at the costs, then double that and double that again and you will be close."
Nice stuff Rodger and, to the extent of its authenticity, can be considered evidence sufficient, if you ask me.