I run my own IPv6-only AS, mostly to get some real-world BGP experience, and partly so I can say I operate my own AS. In fact, IPv6 for this domain is served by my own AS uplinked through the ColoClue network. When running your own AS, you will need to have some way of announcing your IP space through BGP. Some networks and providers, such as aforementioned ColoClue but also Vultr1 allow you to announce routes over BGP after verifying your authority over the announced prefixes.