Steam offers downloads of the Frozen Synapse 2-Pack for Windows or Mac (pictured) for $12.49. That's the lowest price we could find by $38.

Of note, Steam also offers downloads of the Frozen Synapse: Soundtrack Edition 2-Pack for Windows or Mac for $14.99. That's the lowest price we could find by $45. It includes two copies of the game, but one copy of the soundtrack.