There's a free version of Realsoft 3D 4.5 on this month's (issue 75) 3D World magazine. Not sure how good it is though, but it does export to 3ds. I'll have a look through my back issues of 3D World magazine for a free version of Cinema4D as well.
*EDIT* There's a demo of Cinema4D at issue 62, but that was as far back as I got with that.
*EDIT* There's a demo of Cinema4D at issue 62, but that was as far back as I got with that.