Amazon offers its Prime members the Vdera Sharkfin Self-Molding Earbuds in Grey, model no. SF-E-7-AMZ, for
$4.31 $5.05 with free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, it costs an extra $6.51.) That's $5 off and the lowest total price we could find. They're water resistant and purport to mold and fit your ear within five minutes.