Newegg offers the Corsair CSM Series 550-watt ATX Power Supply, model no. CS550M, for $59.99. This $20 mail-in rebate drops it to $39.99. With free shipping, that's the lowest total price we could find by $20. This 80 PLUS Gold-certified PSU features modular cable design with two PCI-Express connections, five Serial ATA connections, and purports 90% efficiency at real-world load conditions.