I have a Phantom 3 (But still a newbie). I’m going backpacking in south east Asia and I am looking for at case for when I am going flying from one place to the next. I would like something that is easy to carry and store away when I am at my destinations.  

Look on Amazon, and read through the reviews. I bought one for my Phantom 4 Pro, and it works great. It will not work with your 3 though.

I bought this one:  Ivation Extra-Light Custom Molded Backpack for DJI Phantom 4 Quadcopter Drone & Accessories on Amazon.  In the title it says for the Phantom 4 but it fits the Phantom 3 Standard fine.  I did cut the controller pocket a little bit to fit my controller.  Best way to cut foam is with an electric carving knife, also available on Amazon for about $12.

This case has shoulder straps for carrying like a backpack.  

I bought a soft case for my P3S as they just seemed to be more expansive than the hard case with foam inserts pre cut out. I can get my P3S, transmitter with Argtek antenna's, 2x tablets (1 7", 1 8"), 3x DJI batteries, a collapsible tripod and SJ4000 sports camera in it's own case with accessories, ND filter set, spare props, 2x power banks and a few other odds and sods. I don't think I would get all that into a hard case.

https://www.amazon.com/Water-Res ... =dji+phantom+3+case

I got this one, works great and is really light even when fully loaded

I would definitely suggest a hard case of some description as I've often seen fellow passengers ram their hand luggage into the overhead lockers without a thought to other persons items.

For my case I bought the ofical dji hardshell backpack on eBay for about $70 but I think you can find cheaper.
Safe travels and flying!