Not that I do not have respect for Linux, but that doesn't sound like much in an age when we're reading about modern aristocracy buying up useless microblogging platforms for forty-plus billions. :)
But if Walmart needed a kernel for some reason, and it would provide value to them, they could afford it, it's about a quarter's worth of profit. But, again, Linux would likely do anything they needed, and if it was missing something they could add it.
the actual cost is in person-years of work, not dollars, and even then you can only speed up the time it takes so much by throwing money at the problem.
This is highly unintuitive. I don't understand how Windows's Explorer (the file manager) has been for many years and is still to this day vastly inferior to Dolphin, a Linux file manager made for free by five Dutch guys or whatever. I can think of many other examples.
If anything, it seems like more money results in less quality, by way of some tragic sociological paradox. :p