At least in the US/EU there is no such thing as a "carrier license". You simply register with an RIR, Pay to "lease" an AS number, request (or buy/transfer) address space.
Once you've done that, buy transit from a provider in your data center or office building, set up a BGP speaker (Quagga, BIRD, GoBGP), and announce your IP space (has to be at least a /24 for IPv4, and a /48 for IPv6).
Sorry, I should have specified I was talking about AU.
To sell internet connectivity here you must have a carrier license from ACMA. I've heard that it costs ~3k to get one. Which makes setting up an neighbourhood ISP just expensive enough that no one bothers. (this is on top of all the normal costs you mentioned)
Once you've done that, buy transit from a provider in your data center or office building, set up a BGP speaker (Quagga, BIRD, GoBGP), and announce your IP space (has to be at least a /24 for IPv4, and a /48 for IPv6).
This whole process can be done in under a month.