The Moxes are a zero casting cost artifact that give one mana of the color it's associated with- so, the Mox Jet gives black, the Mox Emerald green, et cetera
Good thing I have though, as my thoughts about this list have changed quite a bit over the last handful of days
Anything you get to usefully spend mana on later in the game for free (or just the cost of not having a coloured mana earlier at some point) will give you a vastly improved late game
While I havent personally ordered from this company, Id wager that most of your cheaper outsourced sleeves come from manufacturers like these
As long as you're in a format where you can play Fetchlands to fuel your graveyard, it's essentially an upgraded Llanowar Elves that can heal you and damage your opponents without having to go through their creatures
Alternatively, you could use cards like Elixir of Immortality and Teferi, Hero of Dominaria to ensure you cant deck