I can't find the following packages in Debian testing:
http://packages.debian.org/source/sid/nvidia-cuda-toolkit
No more than month ago when I was setting another CUDA box and they were there, now there's only version 3.2 of the toolkit. My sources.list:
deb http://debian.linuxmint.com/latest testing main contrib non-free
deb http://security.debian.org/ testing/updates main contrib non-free
deb http://www.debian-multimedia.org testing main non-free