Woot offers Amazon Essentials Mens Cotton Boxer Shorts for $7.41 free shipping with Prime. 

Product Description:
We listen to customer feedback and fine-tune every detail to ensure our clothes are more comfortable, higher quality, and longer lasting—at affordable prices for the whole family.

• FIT: Slim fit through hip, thigh and leg opening. Sits below the waist
• COTTON JERSEY: Soft, smooth cotton blend. This breathable lightweight natural fabric feels soft against your skin, while the added spandex offers a flexible fit that moves with you
• BOXER SHORTS: A casual shorts design with longer leg length (7"), offering both comfort and functionality for everyday wear
• DETAILS: Designed with soft elastic around the waist for support. Super soft flexible stitching on the leg opening for comfort and stretch and a printed label at the back waist