The Wizard is capped at 1 trigger a turn, but also triggers off enchantments, artifacts, and planeswalkers
The best Dragon commander in MTG is The Ur-Dragon excels for classic tribal value, Tiamat offers precise tutoring and combo setup, and Miirym dominates with explosive board states
That said, collectors are a driving force in Magic's secondary market, and as soon as you put a number on a card (beyond its power and toughness, anyway), you're going to get people willing to spend more than $250 on it
The more cards you can get into hand, the more likely those favorable options will be available when needed
Uurg, Spawn of Turg A good enabler for The Gitrog Monster, Uurg, Spawn of Turg suffers from being slower than the really good graveyard land combos