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?)
NM-Mint - $12.10
Lightly Played - $10.90
Moderately Played - $9.70
Heavily Played - $8.50
Damaged - $6.10
NM-Mint Non English - $12.10
Lightly Played Non English - $10.90
Moderately Played Non English - $9.70
Heavily Played Non English - $8.50
Damaged Non English - $6.10