Theyre very common, seeming to appear in about one in four packs
Aang, Airbending Master (TLE) $14 Aang, Airbending Master is a strong addition to blink decks, because each creature you blink gives you experience counters and thus more ally tokens
You can find a small discount for LP copies, which clock in at $130, with bargains available on MP copies at about $77
And it even comes with a built-in way to put counters on itself via Station
In an unpowered cube the answer to the question how much artifact and enchantment removal to play is that you run is as much as you can that fits the bill of not being a bad card when not able to Disenchant stuff
Shatter the Sky (~$0.22) and Vanquish the Horde (~$0.28) are among the cheapest effective board wipes, both well under a dollar