Ability to purchase OST

Throughout the roughly 6 years that I have been familiar with this game, I have always loved the OST to death and back. I used to play dominion (rip) only for the soundtrack, Summoner's Call still gives me goosebumps and just when I thought loading screens couldn't get any better, Jhin happened and straightup blew mind.

I would love to be able to listen to these kinds of pieces on the go and as I live in a rural area with crappy connection, Youtube is not an option. I would feel bad about just downloading them via an app, because I'd love to support the artists behind the music. Is there any way to do so?