You don't actually need an ASN to get PI though? You can use PI just fine with BYOIP. Actually... I don't think you are even required to announce them on the Internet.
You need the coöperation of the ISP(s), but what you can do is get PI space, run BGP on your router, and use a private ASN (64512-65534) to advertise to your ISP, and then your ISP advertises to the world with their ASN.
One common scenario is two links to the same ISP, so everyone knows which link is active (you can do active-active (load balancing/sharing), or change weights or local preference for active-passive):
The whole BGP process with a private ASN that the ISP strips out and replace with their own ASN on the Internet is how "BYOIP" (bring your own IP) usually works.
