Soft Camera Lens Pouch for $2 + free shipping
Meritline offers this Soft Camera Lens Pouch for $2.29 with free shipping. That's the lowest total price we could find for such a case by a buck, outside the mention below. It measures 3.8x4".
Expect this item to take two to three weeks to arrive.
A close price: pangshionline via eBay offers a similar case for $2.43 with free shipping.