Amazon has the Calvin Klein Underwear Men's Cotton Classics 4 Pack Boxer Briefs (Black) for $25 with free shipping on $25+ or with Prime. List price: $43. Has good Amazon Reviews.
Amazon has the 5-Pack Gildan Men’s V-Neck T-Shirts (Assorted Colors) for $9.00 with free shipping on $25+ or with Prime. List price: $15. Available in select sizes S to XL.
Has good Amazon Reviews.
Amazon has the 6-Pack Hanes Men's Comfortblend Max Cushion White Low Cut Socks (Size 6-12) for $7.00 with free shipping for Prime members or on $25+. Temporarily out of stock but still you can purchase it.
Has excellent Amazon Reviews.