Generally which is the cost of the source programs with relation to the cost of development of a software?

Don't get your question.

1. "Source Programs"... by that, do you mean "source code"?

2. I don't think you're being fair in not even mentioning what TYPE of program: the budget for a high-end 3D video game with 40 hours worth the game play worked on by a dozen cgi animators, two conceptual artists, 7 programmers (one just for geometric texture algorhythmic calculations), etc. is going to differ from that of rather simple audio editing application some lone guy or gal did as a side project in IT school.

For example: one of the games made by ID Software purportedly cost (according to the guy interviewed) about a million dollars to make, but they sold like 15 million units that didn't cost a buck a piece, so that was a success. I believe the engine they used was their own proprietary game engine; you can tweak/modify it to your heart's content, but you couldn't sell your creation or even license it through them.

On the otherhand, I've heard of a game engine called "Torque" that can retail for under $500. I'm not saying it's as aggressive as ID's, but if their engine was available retail around the same price, that means (saying hypothetically that in this case we can call the game engine the "source program" and the 'shell' that's wrapped around the engine the software application, the cost of the 'source program' in relation to the cost of the development software is quite negligible by comparison...in this scenario.