Woot offers Sun Joe SJ-MMPH1 3-In-1 Soil Meter | W/ Moisture, pH, and Light Meter | For Indoor/Outdoor Garden for $7.99. Free shipping for Prime Members.

Product Description:
GROW WITH JOE!  Keep your soil + plants in peak health with the convenient SJ-MMPH1 3-IN-1 SOIL METER from SUN JOE.
The secret of great gardens and gardeners, this powerful 3-in-1 tool tests for proper moisture, pH and sunlight for healthier soil + happier plants.
Designed for easy indoor/outdoor use, it’s great for testing condition and plant care in lawns, gardens, greenhouses and homes – no batteries required!
Just water before testing and select your desired soil testing mode and you’re all set! When finished, simply remove the probes from the soil and wipe them clean. 
Features

• 3 Modes: moisture, light, pH
• Light sensor: measures light intensity levels, 0-2000 LUX
• Moisture sensor: 7.9” copper probe for 10 moisture levels
• pH sensor: 7.9” aluminum probe, 3.5-8pH scale
• Gauge readout for easy monitoring
• No batteries required
• Lightweight at just 2 oz