Just an update on the Amazon Basics Orange DSLR bag that I have owned for a couple of weeks now. I can confirm it is an excellent and inexpensive option for carrying the P3. Its not the highest quality but at $34.99 its actually PFG. It is just about a perfect fit for the P3, in fact its just a little bit tight for the first few uses but the material must stretch ever so slightly because it is now perfect. Good protection for the money - OK its never going to be a replacement for a hard case or foam cut-out bag, but if you wan't something discrete in the smallest possible package then this is a great option.
I carried my P3A back from the U.S onto the plane with me, it fits easily in the overhead bins and is thick enough that nobody should be able to put anything on top of it, which was my main concern. I had to bring my laptop back with me as well and even this fits in the bag too, in the rear compartment.
I have carried it out walking etc. with the Phantom and its great, I can fit, the Phantom, batteries, charger, props, spares, RC and tablet or phone.
Hope this helps some folk.