I used to have a DPT-CP1 digital paper tablet (which is similar to the remarkable) so I bought this nice leather folio case for it. After a while I moved to the remarkable tablet and to my surprise the exact same folio fit really nicely to it (with a few minor adjustments that I will show how to do). The price is a lot cheaper than many options out there, and being a leather case it's for me the best alternative. Also the pen holder fits perfectly.
1. First you have to remove the leather strips that are used to hold the sony's tablet. You do this (very carefully) with a cutter as close to the bottom as you can). So you finish with something like this:
2. Secondly you will have to buy something to stick the tablet to the cover, I used this 3M command strips that are used for hanging pictures on the wall. You'll have to put 2 of those in the remarkable tablet as shown below, and only one on the cover (as it already has one by default).
3. Lastly, remember the strips you removed from the cover on the first step? You can use that to place it in the cover (shown below) to fill the small gap that is created between the remarkable and the cover itself due the sticky strips we placed there. Is a bit of a tedious work, but for the price and the convenience (once you finish) is totally worth it, I have been using that cover non-stop for months now.
Any ideas feel free to colaborate :)
NOTE: You can find the cover in black as mine or in a nice Navy blue.