As Marcio mentioned they are shipped flat in boxes. I just received my order last week from Dick Blick for 10 sheets so I will share how they packed it. I was quite impressed.
They used reinforced cardboard for protecting the corners within the box, and these reinforcements were taped well so the paper did not move at all! Since I recently moved away from a large city I was a little wary. However, I am happy to say that my paper arrived in excellent condition which is always a pleasant surprise.
I am sure the other large online stores pack the paper in the same type of manner.
I agree with Marcio that the paper bought in a store is more likely to be damaged, specifically fingerprints which can affect the surface. The bummer with that is that it isn’t noticed until AFTER you have applied your paint.
Each online retailer seems to always have a “sale” on watercolor paper and with the way it is packaged it lasts a long time.
I hope this helps.
Debra
[FONT=Arial]Debra
[FONT=Arial]"The future belongs to those who believe in the beauty of their dreams." - Eleanor Roosevelt