Skins and how to obtain them

Hello so ive been looking for police skins for the Ishtar i will be able to fly soon and maybe a few other cruisers and below. So i went to jita and saw the price for ishtar police skin is 1.4 bil and up. As a new player i dont have that kind of money to blow and was wondering how everyone got those skins in the first place. I figured it was from some sort of event or mission i can run. I was wondering when an event like that would happen again or what i can do to obtain one

There is a store that you can get to through your character menu. It is called the New Eden Store. They sell stuff like skins for PLEX, which you buy for real-life money. Most skins are acquired that way, although there are also a significant number of skins that come from events, including Project Discovery, NPC mining fleets, and abyssal stuff.

Most SKINs are bought from CCP with PLEX via the New Eden Store (NES). Some are granted from events (like the empire celebration days, EVE birthdays, Project Discovery, etc), and a few come from drops like Xeux mentioned, but most SKINs are bought with what amounts to real money (as all PLEX comes from a real money purchase by someone).

The last time the Police SKINs were made available was, I believe, the January 2019 promotion in this notice:

At an original NES price of 110 PLEX, the Ishtar SKIN cost approximately $5 USD at time of sale (if PLEX was bought in the smallest package) - which equated to about 484 million ISK at the PLEX-to-ISK market rates of that time.

18+ months later, the PLEX-to-ISK value has plummeted, but the SKINs are now a limited commodity, so their price is higher for collectors who really want the SKINs -now- and not have to wait in hopes of CCP listing them for sale again.

EDIT: Some Police SKINs may have cycled through again in mid-2019? Not entirely sure if the Ishtar was one of them, or if these were more new SKINs being added for a few weeks. CCP is really erratic about how they advertise NES stock changes, and not all sources specify which SKINs were in the referenced sale.