With tablets, there are three major sizes: 7", 9.7", and 10.1". Often times, generic cases and other accessories are difficult to come by if you are not in one of those categories. I would imagine since this is not a very popular tablet, accessories would come at a premium price unless found on clearance. I used to own a Toshiba Thrive and I was able to purchase a generic keyboard case which saved me ~$30 compared to the one made specifically for the Toshiba Thrive.
Reviews I've seen recommend the Kindle Fire HD 8.9 cases. Though from what I've seen on spec sheets this tablet is slightly thicker so it will probably be a tight fit depending on the case.
Personally, I was going to buy this tablet a few weeks ago for around $230. But I had to go to Best Buy to take a look at it. The screen really is terrible, very unforgiving on the viewing angles, colors wash out quite easily if not held just right. I would pay a little more money for something with a better screen.