Unlike other theft decks, it is really hard to prevent Tergrid from stealing your stuff, as they aren't safe in your hand or on your board, and thanks to other Mill and reanimation effects in Black, they probably aren't safe in your library or graveyard either
Two instances of instant-speed flicker on one white instant is still a good deal
Card prices are driven by supply and demand, but also by history, rarity, collectability, tournament relevance, and formats like Vintage, Old School, and Premodern
Stay tuned for more information
Even with multiple reprints, with the most recent being the Enchanting Tales version from Wilds of Eldraine, this is because it's a powerhouse of a card
With that in mind, it helps to include as many haste granters as possible like Goblin Chieftain and Goblin Warchief