[CKN23-ARIN]

The smallest routable IPv4 network on the Internet is a /24, which is 256 addresses. Regional Internet Registries won't assign you smaller than a /24, but individual ISPs might. Even if you have an assignment, maintaining it requires payment of annual fees to your RIR, unless you're a lucky "legacy" address holder from before the RIRs were formed.

[icedchai]

I own a /24 from the early 90's, registered before ARIN and the other RIRs existed. It is considered a legacy block and I've never signed the legacy registration agreement, so no fees for me! I do have it routed to my home network over a "business broadband" connection.

[CKN23-ARIN]

Jealous! I pay ARIN hundreds of dollars a year in RSA fees.

As a legacy address holder, how do you feel about RPKI?

[icedchai]

I use my network mostly for experimentation and it is unlikely to be a target for hijack. If I were a commercial enterprise I would want RPKI for the future. Currently it seems mostly irrelevant in a practical sense, due to the small number of ASes actually validating.