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 - $13.00
Lightly Played - $11.70
Moderately Played - $10.40
Heavily Played - $9.10
Damaged - $6.50
NM-Mint Non English - $13.00
Lightly Played Non English - $11.70
Moderately Played Non English - $10.40
Heavily Played Non English - $9.10
Damaged Non English - $6.50