Home Depot has 2-Pack Lutron Maestro 2-Amp/Single-Pole Motion Sensor Switches (White, MS-OPS2-WH-2) for $34.97. Shipping is free.

Features:

• Motion sensor switch automatically turns the lights on when you enter the room and off when you leave; covers major motion in a room up to 900 sq ft
• Features XCT sensing technology which detects fine motion (up to 20 ft. away), such as typing at a desk or reading, ensuring lights do not turn off inadvertently
• Smart Ambient Light Detection: Senses daylight in the room and learns your preferred light level over time, so your lights stay off if it's already bright
• Programmable time-out of lights – set to turn off 1, 5, 15 or 30 minutes after leaving a room
• Vacancy-Only Mode: Can be programmed as a vacancy-only sensor to meet Title 24 requirements
• Flexible Install: Install using the ground wire if no neutral is available in your home
• Single-pole only; great for small rooms like bathrooms, laundry rooms and closets
• Installs in as little as 15 minutes; works with to 150-Watt LED, 250-Watt incandescent, halogen, electronic low voltage, 200-Watt magnetic low voltage, or 2-Amp ballasts
• Includes (2) 2-Amp Maestro sensor switches; coordinating wallplates sold separately