Keychains: Print on shrink plastic, color, punch a hole, and bake
Obviously, you get the most value out of just casting it face down and turning it face up at which point you paid 5 mana for a 3/1 Vigilance and two 1/1s, and paying it in installments will make it feel more efficient than that
The better its condition, the more you get
The Monsters II Razaketh, the Foulblooded (Gore Magala, Dark Eclipse) - $10 Nonfoil / $16 Foil Kalamax, the Stormsire (Brachydios, Brutish Indigo) - $0.55 Nonfoil / $0.65 Foil Wasitora, Nekoru Queen (Nargacuga, Ever-Present Shadow) - $0.60 Nonfoil / $1 Foil Amareth, the Lustrous (Velkhana, Silver Sovereign) - $0.50 Nonfoil / $0.70 Foil Total = $11.65 Nonfoil / $18.35 Blech, once again there's only one card in this drop worth mentioning
(4/17/2020) If you reveal a companion outside the game, for as long as it remains there, you may pay any time you could cast a sorcery (that is, you have priority during your main phase and the stack is empty)