Budget Alternatives to Metalwork Colossus

Dutiful Griffin $0.04 3WW · Griffin Flying Molderhulk $0.16 7BG · Fungus Zombie Undergrowth — This spell costs {1} less to cast for each creature card in your graveyard. Phantasmagorian $0.20 5BB · Horror When you cast this spell, any player may discard three cards. Eldrazi Ravager $0.27 5C · Eldrazi Annihilator 1 Volcanic Salvo $0.28 10RR · Sorcery This spell costs {X} less to cast, where X is the total power of creatures you control. Sproutback Trudge $0.31 7GG · Fungus Beast This spell costs {X} less to cast, where X is the amount of life you gained this turn. Salvage Titan $0.31 4BB · Golem You may sacrifice three artifacts rather than pay this spell's mana cost. Oskar, Rubbish Reclaimer $0.36 3UB · Human Wizard This spell costs {1} less to cast for each different mana value among cards in your graveyard. Capricious Hellraiser $0.36 3RRR · Phyrexian Dragon This spell costs {3} less to cast if you have nine or more cards in your graveyard. Demilich $0.64 UUUU · Skeleton Wizard This spell costs {U} less to cast for each instant and sorcery spell you've cast this turn. Ghalta, Primal Hunger $0.66 10GG · Elder Dinosaur This spell costs {X} less to cast, where X is the total power of creatures you control. Nyxborn Behemoth $1.37 10GG · Beast This spell costs {X} less to cast, where X is the total mana value of noncreature enchantments yo... Sunderflock $1.80 7UU · Elemental This spell costs {X} less to cast, where X is the greatest mana value among Elementals you control. The Cauldron of Eternity $1.94 10BB · Legendary Artifact This spell costs {2} less to cast for each creature card in your graveyard.