A couple of years ago, I picked up a couple of simple accordion files from the local Office Depot which I've been using to carry my PR materials like novel sell sheets, book catalogs and anything else I'd likely need as I visit various book stores. There was even a larger slot at the back where I could carry a couple of the books. It's worked well with only a little fraying around the edges and some sag in the elastic band around the case.
While thinking about what kind of case I could use to carry my iPad editing station (iPad, dock stand, and bluetooth keyboard) I happened to glance at the blue case. I flipped open the top and was pleased to discover that the keyboard, with had the longest dimension of any of the components, fit easily in that rear slot. The iPad had no problem slipping into one of the other slots and the dock, while not a tidy flat item like the others, still fit under the fold-over lid with no problem.
This "found" case is just about perfect for what I need. Everything fits. I still have lots of room for my PR materials, and if I feel I need more padding for the iPad's safety, I can put it into one of my bubble-sided mailing envelopes and it would still fit in the accordion file.
At the moment, I'm sitting on a picnic table in the park, taking a quick break from my story editing to add this blog entry, and it's working perfectly. One added bonus is that it doesn't look odd. If I don't want to attract attention to my iPad, I don't have to.
One important tip, if you're using a wireless keyboard like this. Turn off the Bluetooth in the iPad's settings when you pack up. The case does nothing to keep the keys from being pressed accidentally. This wakes up the iPad. So even if I've packed it away turned off, just picking up the case is likely to turn it back on and use up battery. Luckily, it's easy to get to the bluetooth controls.