Store economy advice for new gacha player

I’ve dabbled in a few gachas but haven’t played any seriously enough to spend. The factory system pulled me in and I’m liking it combined with the rest of the game to the point of wanting to stick around.

So I’m trying to understand the banner character system. From what I have gathered from posts here, it takes 120 tickets to guarantee the character, by 80 you have a 50% chance for that or other 6-star, and I really shouldn’t pull unless I have 120 because the pulls don’t carry over to the next banner.

I’m looking at the store thinking what would it cost to buy a character if I like the game enough to support it. The store has a 10 pull for $15, and it takes 120 to guarantee? Unless there’s a fundamental part of the economy I’m missing, that seems like an insane amount of money for one character.

Maybe that’s just how gachas are or maybe there’s another critical piece of info I don’t have about the system that someone could help clarify for me.