Nice. Like Gary, it took a while to figure it out.
For example, to see a price come up, you have to select a product and then you are prompted with "Please select the quantity you wish to order from below:" and you see some prices - I know this should be obvious but it isn't. If it were possible to show the price below at zero before anything is selected it would be more obvious what is going to happen. (It does become clear where you read the text, but you know what people are like.)
I tried to work the site like a traditional online shopping basket (the default for most people I would guess) but I could not see what I had selected and added to the basket so to speak. No way to select a number of different items and process them. You would know better than me what the normal process is for most people. I may be strange but when I have ordered this kind of stuff in the past I have gone in thinking ..." I need x flyers of this size, and y of that size; z thousand full colour and xxx thousand 2 color spot" and want to cover off my formats before specifying he content of each.
One other point. Possibly just me. When I first clicked on the link to your site without any though as to who you were, I could not at first figure out what you did. Perhaps if I had been googling, I would have known what to expect. The order I noticed things in:
1. Pay Online £
2. Upload Own Artwork
3. Get High Quality Print Delivered Fast To Your Door
4 White Spark Promotions
5. Special launch offer - but could not read it easily so looked elsewhere
6. Design Online
7. Leave a message offline
8. Authentication
9. Menu (already aware but looked at it, and then it dawned on me what you did)
Stuart