Are you ready to embark on a quest to own the most sought-after cards
If you have a good rare or mythic that would fit the deck and improve it, then by all means add it
Sweeping menace for your creatures is already pretty good, but stealing cards that you milled is even more diabolical
Air Balloon is now rightfully considered a staple card for all energy-based decks, so it shouldn't come off as a surprise that it currently holds such high pricing for a basic tool card
In general, if you're willing to pick up a heavily played version of a card, you can usually safe close to 50% off of the headline near-mint price, if you're willing to dig around a bit
While not a high-value investment, its a format-defining role-player that sees play in Pioneer, making it a great pickup for players on a budget