Currently, there are small digital cameras like the Blackmagic Pocket Camera (BMPCC) camera, under $1k, which have a capability to shoot images that are so similar to 16mm film that the average consumer couldn't tell.
The bottom-line today: if you want the 8mm vibe, you oversample your image when shooting (16mm or 35mm digital) and then degrade the image in post-production to 8mm.