Probably not a very different price, and the end result might not be much better. Bespoke enterprise software is notoriously expensive, and the end results are often not good. Lots of reasons, many the same as with government: client has very particular needs, client has unclear specifications that are changed several times during the process, competition for the bid is weak, client doesn't have their internal shit together, client's existing systems that the new stuff must integrate with are poorly designed and/or bitrotting and/or broken, client's management/billing/procedures are so bureaucratic that you have to include some cost in the bid just to pay for that, etc.

I haven't done anything in that area myself, but from what I hear second-hand it's a gravy train once you've made a sale to a Fortune500 company. Sales is hard, but once you've made the sale, you can bill millions for years for all sorts of reasons, some of which are even legitimate (given what they're asking you to do).

For just webapp? about order of magnitude less I think 3-4mil . Still way too much

It's probably in the similar range, but private companies are private. They have no obligation to anyone other than stockholders.

That may depend on whether that large private corporation is already running the US Census.

Hopefully that day will never come, it is enough that corporations are running the prisons.

I would also like to know how much said private corporation would charge. (But I don't have to wonder very much, because companies like Elsevier and Lexis/Nexis give a pretty good idea)