Lowe's [lowes.com] has the Klein Tools RT250 GFCI Outlet Tester w/ LCD Display on sale for $19.98 with free store pickup.
Great reviews on this outlet tester.
- Features:
- Large backlit LCD readout for voltage reading and wiring condition indication
- Trip time display shows time required to trip a GFCI device
- Detects and identifies common wiring faults in GFCI receptacles
- Patent-pending Open Neutral and Open Ground fault detection
- Auto-Hold function holds reading for hard-to-reach outlets
- Compatible with standard 3-wire 120V electrical receptacles
- CSA certified
- Specs:
- Model: RT250
- Operating voltage: 120V AC
- Measurement type: Voltmeter
- Weight: 4.16 oz
- Dimensions: 4.53" x 1.16" x 2"
- Upper temperature rating: 60°C
- Includes:
- RT250 GFCI outlet tester
- 2x AAA alkaline batteries (1.5V)
- Manual