After being frustrated at not finding any of these in close to a dozen locations near me, I finally bought 3 from Ebay, and then resold 2 of them immediately to members of another forum. Just completed a 2 week trip, charging at many Walmart locations. On bathroom breaks I checked for the car, and when I found it, bought it. I now have a bunch of them.

If you are interested, let me know. Payment via PayPal Friends and Family. $10 in a padded envelope via First Class mail (tracking), or $13.50 via Priority Mail in a padded envelope (tracking and insurance), $15 in Priority Mail box.