Adam,

Your site is well done and obviously the photos are excellent. I would add a few comments:

1.  Most sizes are a 2:3 ratio but a 6 x 6 size is offered but no sample of how the photo would be cropped in a square format.

2.  Many people will not know what A3 and A4 sizes are; I would add the measurements, including the units.

3.  Where you have shown sizes, I would add units to remove any doubts people may have about the actual size.

4.  I disable specified backgrounds and just use a white background and your site looks quite well this way, in fact I think it is better than the black background because reading white letters on a black background works okay for about 20 words, then it becomes a major eyesore.

Best of luck with your endeavor!

Wayne