Walmart offers Spider-Man: Into the Spiderverse Boys Underwear, 5 Pack Boxer Briefs Sizes 4-8 for $4.10.  Shipping is free with Walmart+ or on orders over $35.

Product Description:
Boy's Spiderverse 5pk of boxer briefs made of combed cotton with elastic waistband for comfort. Tagless for extra comfort. Features characters from Spiderverse.