Hi Kat,
The largest screens you can buy are 9.7" but that is too large.
I can highly recommend the Astak EZRead series of ereaders. They are sold from the US, but they ship and support the device Internationally. I bought last year their 5" Pocket Pro (which sells for $199US + shipping). They have a 6", which I believe is around $235-$255US. Both come with protective leather covers.
Like most ereaders, they support Adobe DRM'd epub and pdf books (which is the most common format for ebooks).
You can checkout the Astak thread here on the forums if you'd like more information on the readers. I highly recommend the device and service, or their website
www.astak.com. I am not affiliated with them, just a damn happy customer.