Macy's discounts a selection of Nike men's swim apparel, with prices starting from $11.86. Pad your order with a beauty item (they start at $3) to bag free shipping; otherwise, shipping adds $10.95. (In-store pickup may be available.) A couple of best bets:
Nike Men's Breach Volley Shorts for $12.76 ($45 off)
Nike Men's Swift Striped Volley Swim Trunks for $12.76 (pictured, $45 off)
There's a less expensive way, and then there's the way that works for you. The two may not be the same.