Cheap because the mana problem is solved with cards, not purchases.
The previous version paid $4.41 for a slow rainbow land pile. This version starts with your basic lands, finds the exact colors it needs, and spends the savings on cards that make bodies, fill the graveyard, or answer a problem. That is the same bulk-bin logic that made the Vehicles deck work.
How it plays: use cheap green search and color-fixing auras to put the right basics in play. The same low-cost token spells that stock the board become Niv’s convoke mana. Your upkeep turns one cheap flashback spell, removal spell, or token-maker from the graveyard into a free extra cast. Guttersnipe and the token finishers turn that repeated casting into a clock.
Price reality: $13.11 is the live item floor for the 62-card buy list shown here. It excludes your owned Niv-Mizzet, Supreme, 37 basic lands, tax, CardTrader Zero fees, and final cart-assembly changes. Mortify was unavailable in English CardTrader Zero inventory at cart time, so the live list uses English Murder instead. Use dice or spare cards for the Wizard, Servo, Goblin, Saproling, and Fractal tokens rather than purchasing token cards.