I... what? That question goes all over the place, so I'm not sure what you're talking about.
You can and should farm all Guardian Eidolons eventually. Using one of those and a P2W Eidolon is an extremely good combination.
No idea what your second sentence is about. You can get a guaranteed SSR for 30 bucks, yes. It's a waste of money on Eidolon side, though, since you will NOT be finding a P2W Eidolon from that and the otheres are trash until MLB. If you're after Anubis, you'll have to buy the 100 bucks MT.