$6k per person to cryopreserve everyone?

While better than nothing, I am skeptical that a good enough MRI or CT scan can be taken to preserve one's personality to the degree that preserving the brain physically could do. Chemical preservation is one inexpensive option that has been around for centuries -- Ben Franklin mentioned the possibility, and some brains such as that of Charles Babbage are still preserved. Brains preserved this way and scanned at a later date would yield much better data than the best brain scans taken today.

However, even this is probably a lot less fidelity than cryonics at its best. The vitrification process actually preserves a significant degree of cellular viability. For example, a rabbit kidney has actually been successfully implanted after cryopreservation. So if we are trying to maximize the degree to which someone avoids death (acknowledging that some degree of death / memory loss is probably inevitable, for now at least), cryonics is likely to be the best available bet.