Pro-LifT Green 300 Lbs Mechanic Creeper – Link

Amazon has this currently marked down to just $34.99 w/ free shipping.

• Easily converted from creeper to seat for your maintenance convenience
• Thick padded cushions create a comfortable base for easy access and movement during your maintenance tasks
• 6 swivel casters for easy maneuverability. Vinyl padded seat and headrest
• 300 pounds weight capacity
• Easily retractable pin to change seat