If you're paying more than that, they're ripping you off.
Since the product descriptions are quite terse, I'm not sure what is an "INbox mailer", or what's the difference between "Smtp Inbox Ip" and "Smtp inbox Domain". A "Shell" or "cPanel" is self-descriptive, that's a simple access to *nix or a web-based hosting system. RDPs are for Windows remote access. But if you're buying 100k e-mail addresses, why are co-operate ones twice as expensive? That I don't know.
If you purchase those services, please let me know!