I recently had my 8 year old pair of Serengeti Velocity's stolen from my car (I use them for both flying and driving). I initially had the same problem you did sourcing a replacement pair but eventually I found some. Checking Serengeti's website they still offer non polarized sunglasses but generally retailers don't stock them because polarized lenses are more popular. If you really want Serengeti you'd probably have to order them in through a retailer or direct from the factory.