INCIPIO Feather for MacBook Pro 15" Retina Non-Touch Bar Model (Translucent Blue) $3.62 + Shipping ($0 C&C/ in-Store) @ PB Tech

$18.77 showing normal price. Grey is available too but for full price.
Its great quality and price, as i remember they used to be retailed at $70+.

I have one but in grey color, helps with avoiding cosmetic damages etc.

Ultra Thin Snap-On Case for Macbook Pro 15 Inch

Incipio's protective, form-fitting feather Case prevents unwanted scratches and dents to your device. Rubber feet adds no-slip grip to enhance your computing experience whether at home or traveling on the go. The translucent case is available in a variety of color options to match your personal style.
Features

• Sleek and transparent design lets the Apple logo show through
• Rubber feet provides added grip for secure typing
• High density Plextonium polycarbonate construction for premium durability
• Specially engineered to provide lightweight and travel-friendly laptop protection