I got mine from ebay, but I hear nothing but good about newenough.com. I ride in TX and it's HOT. Mesh is the only way to go for riding in hot weather. Like jmatt said, if it's hot outside sitting still is going to be hot no matter what you've got on, but as long as you're moving the mesh does a good job.
I smile 'cause I don't know what the h*ll is going on.