Ah, Seven Seas, where good manga goes to die. Horrible value proposition, even for those who like buying Manga. Plus, apparently they translate / update really slowly.
Personally, unless someone offers a monthly sub that's $5 a month or less, I don't even bother. I just rotate between sites / apps that offer a plan like this. Manga Plus, Mangamo, Azuki.co, Viz's Shounen Jump, Vizmanga, etc.
But people that charge $10 for a single volume with not that many chapters? No. Also no to people that charge an exorbitant price per chapter. Kodansha being the main culprit with stuff like that. If the payment is a temporary unlock rather than a permanent purchase, that's even worse.
It's why I think that competition is necessary in the manga space, just like any space. Also necessary are archival sites like Mangadex, for if / when publishers go out of business / lose a license, and then Mangadex is the only place to read things when the physical AND digital stuff goes out of print.