As long as Trinisphere is untapped, each spell that would cost less than three mana to cast costs three mana to cast. (Additional mana in the cost may be paid with any color of mana or colorless mana. For example, a spell that would cost {1}{B} to cast costs {2}{B} to cast instead.)
NM-Mint - $31.30
Lightly Played - $28.20
Moderately Played - $25.10
Heavily Played - $21.90
Damaged - $15.70
NM-Mint Non English - $31.30
Lightly Played Non English - $28.20
Moderately Played Non English - $25.10
Heavily Played Non English - $21.90
Damaged Non English - $15.70
Foil Prices
NM-Mint Foil - $39.10
Lightly Played Foil - $35.20
Moderately Played Foil - $31.30
Heavily Played Foil - $27.40
Damaged Foil - $19.60
NM-Mint Foil Non English - $39.10
Lightly Played Foil Non English - $35.20
Moderately Played Foil Non English - $31.30
Heavily Played Foil Non English - $27.40
Damaged Foil Non English - $19.60