Mind Stoneramp$0.31A cheap colorless mana rock that fills the same early-game utility role and can later be cashed in for cards. It is a very common upgrade when you want ramp with flexibility.
Everflowing Chaliceramp$0.19Another scalable colorless artifact ramp piece that can come down early and produce more mana as the game goes long. It serves a similar role as a generic artifact accelerator.
Prismatic Lensramp$0.38A two-mana artifact that ramps immediately and helps fix mana in multicolor decks. It is a close functional substitute for a low-cost mana rock.
Fellwar Stoneramp$1.91A staple two-mana rock that often taps for any color you need in multiplayer games. It is broadly stronger than a colorless-only rock in many Commander pods.
Thought Vesselramp$1.92A two-mana mana rock with no maximum hand size upside. It plays similarly as efficient colorless ramp with a small bonus.
Coldsteel Heartramp$0.99A cheap mana rock that enters tapped but produces colored mana of your choice. It is a strong budget-friendly substitute when you want a similar slot in the curve.
Guardian Idolramp$0.35A two-mana artifact that ramps and can become a creature later if needed. It is similar as a colorless utility rock with extra flexibility.
Commander's Sphereramp$0.24A slightly larger mana rock that fixes colors and can cash itself in for a card. It is a common upgrade path in multiplayer decks that want more late-game value.