So if I found a phone in a public restroom and took pictures of it and posted it on my employers blog, then the original owners contacted me and asked for their phone back and I said yes, several days later a judge could issue a search warrant to seize my personal computers?
Bull.
Living in CA and in the same complex as a sheriff's office, you are missing the key fact that it was noted as being lost and is worth more than $100, which means that the following law applies:
"If the true owner is not known and the [lost] item is worth more than $100, then the finder has a duty to turn it over to the local police department within a reasonable time. Id. § 2080.1. The owner then has 90 days to claim the property. Id. § 2080.2. If the true owner fails to do so and the property is worth more than $250, then the police publish a notice, and 7 days after that ownership of the property vests in the person who found it, with certain exceptions."
Clearly the finder did not do the following, although I would assume the law would be more interested in the original person who found it rather than the one who bought it (the aspect that they knew it was lost was a dumb move on their part to publicly tout that fact).