I’ve found Howard Packaging’s Photo Postcards to be preferable to the PhotoPostos. The PhotoPostos seem to be about the weight of printer paper — if even that heavy. The Howard Packaging Photo Postcard product is available at Ritz Camera. While i haven’t seen them at my local store, they are available online.
Howard Packaging Make-Your-Own 4×6 Photo Postcards; 12+3 Pack
Mfr # 77215
$3.99