Don't gain wealth at the cost of your conscience.

Literal

Conscience [object-を] sacrifice-して wealth [object-を] don't-obtain.

~を犠牲にして ('sacrificing X, at the cost of X') is a set phrase: 犠牲 ('sacrifice, victim') + にする. The negative imperative な at the end forbids the action — a direct, blunt prohibition that gives this sentence its moral-command tone.