And it doesn't really need one. Unity's free version just like Shiva's free version is a pretty perfect entry version. You can start to develop your games with those versions for free and once you see that things come along nicely you actually buy the full thing and in the case of unity e.g. get all the additional eyecandy like dynamic shadows & stuff. For Gamestudio with no shaders, bad editors and so on the start is by far not that great and complete...

I also do not think that Unity's cost are any problem for a serious developer. If you think of having created a game that sells well even if just on an Indie scale level you should have no problem in paying the bills for Unity. That also might reveal a niche 3DGS might fit in and that's the really low budget sector also aiming at those who just do it for fun and don't really plan to release a game that sells so well they even might live from it. That also lowers the bar for the needed features by a lot which is quite accomodating for 3DGS. You would need some easy accessible editors though and currently this fails horribly especially as WED never made its step past the cube code base (or whatever it was that got bought and used to be WED's base from the first days - it sort of was advertised as a feature in the A4 days ) from the last millenium...