organisations already pay for programs with such well written and tested code - Dunn and Bradstreet's Millennium accounting program is one example I know of. The Unix and Linux communities seem able to manage it without adding on a huge extra charge for putting out good tight code without KNOWN faults and for quickly fixing any new faults found.

I doubt it''' be a huge expense to do it the right way. However, those who have huge piles of faulty code will have to spend a lot to fix it up, but that's what they get for being lazy in the first place.