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 - $9.10
Lightly Played - $8.20
Moderately Played - $7.30
Heavily Played - $6.40
Damaged - $4.60
NM-Mint Non English - $9.10
Lightly Played Non English - $8.20
Moderately Played Non English - $7.30
Heavily Played Non English - $6.40
Damaged Non English - $4.60