Amazon offers Prime members the Extech Electrical Test Kit for $19.99 with free shipping. (Sears charges the same via in-store pickup.) That's the lowest price we could find by a buck, although we saw it for $2 less two weeks ago. It includes a multimeter, non-contact voltage detector, and receptacle tester to measure AC/DC voltage, DC current, resistance, and continuity, as well as diode and battery tests.

Update: The price at Sears has dropped to $17.99 with in-store pickup.