Fat-Mango via eBay continues to offer this Folding Credit Card-Shaped Multipurpose Knife in Black for $1.99 with free shipping. That's tied with our mention from a week ago as the lowest total price we've seen for such a credit-card-shaped folding knife. (It's also a low by $1). It features a stainless steel surgical blade and built-in protective sheath.
Expect this item to take two to three weeks to arrive.