The Sweetie & I are going to Port Aransas next month with my sister, her family, and our dad. So far at the Salvation Army, I've found:
A like-new boogie board, $5
Like-new swim fins, $6 (half-off)
This is their flagship store, right across from where I work, so I'm stopping by several times a week. I hope to find swim masks, snorkels (will sanitize), and another set of fins.