Cast a random Lesson spell without paying its mana color. If that spell has X in its mana cost, X is 3. (As of today, there are 20 lessons. Perhaps look up a list and roll a d20?)
Near Mint - $12,700
Lightly Played - $10,200
Moderately Played - $8,900
Heavily Played - $7,600
Damaged - $6,400
Near Mint Spanish - $12,700
Lightly Played Spanish - $10,200
Moderately Played Spanish - $8,900
Heavily Played Spanish - $7,600
Damaged Spanish - $6,400