I bought some (well quite a lot) of screen protectors for the N810.
They basic but are very good, very easy to put on without any bubbles. The size is absolutely perfect.
The reason why I purchased in bulk was duue to previous experience with my PSP where I wasted 6 screen protectors just to get on perfectly. However, these ones are so good and easy to put on, I only needed one and I have it on perfectly without any bubbles.
They come in pack of three's, so the price will only be £4 for 3 screen protectors delivered first class, recorded.
£1 first class, recorded