[q0uaur]

the linked page has an earlier blog entry talking about that:

https://blog.lyc8503.net/en/post/asn-1-asn-registration/

quickly skimming the article i couldn't see a specific price for the ipv4 block, but ipv6 is cheap - the article mentions having to pay at least $50 a year + service fees to a "LIR", and you also need a BGP-enabled hosting provider which i imagine will come with similar cost at least (don't quote me on that).