If that is so easy to be done with GS, why don't you guys implement it? For free or for money?

Of course is it natively implementable in GS. Nothing else I did with LightFrog.

Just because it's easy it doesn't mean it isn't time consuming.
There are nearly no developers who would make effectively use of such a system. Most people here just toy around.
Therefore I wouldn't feel motivated to do it for free.

Ok, nice. But what if those guys which are toying around will pay you some cash? How much will this stuff cost?

Hm, that depends. What would -you- pay for something like that, 3run?

Problem is, that I'm not familiar with prices, that's why I ask. And if someone is going to do that, I guess there will be few persons around the forum, which will team up and pay your price all together, cause that will be cheaper for all of them (me as well).

Such a system wouldn´t really work with any other shaders, that aren´t exactly written to work with it.
So let me do some stupid guess of maybe 100 hrs multiply it by lets say 20€ per hour and you´ve got a price. Those values are btw kinda taken out of nothing, but should at least give you an idea.

Won't work with other shaders? 2000 euro, this is 2 much I guess

edit: zero missed

100h * 20€ = 200€ ?

thats even worst

exactly as slin says too, after 2k spent, you would also need to rewrite all your shaders to work with your fancy new lighting system.