Spells you cast have affinity for artifact creatures that weren't originally artifact creatures. (They cost 1 less to cast for each artifact creature you control that wasn't originally an artifact creature.)
1UU: Target permanent becomes an artifact in addition to its other types.
Near Mint - $15.25
Lightly Played - $14.50
Moderately Played - $12.25
Heavily Played - $9.25
Damaged - $7.75
Near Mint Non-English - $15.25
Lightly Played Non-English - $14.50
Moderately Played Non-English - $12.25
Heavily Played Non-English - $9.25
Damaged Non-English - $7.75