Like most Magic: The Gathering cards, the value of Urza, Lord High Artificer depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Mystery Booster 2)
You won't get any .
This principle extends to the rest of the product lineup, too
He does a pretty good impression of Mother of Runes Playing this on turn two seems pretty sweet, as youre likely to overwhelm your opponent with Mites, and once theyve been hit a few times, the fact they all gain lifelink is great and really offsets the fact that they cant block
You have generally won if you manage to get him in at all, not just because one damage and a card is so back breaking but more because there is a very good chance that if it just happened it will be happening again the next turn too
It might settle out at $20-$25, and thats going to be a good hit