I put paper in my carry-on baggage. As long as you're not buying monster sizes, this should work fine.
Airlines will usually let you carry a shopping bag in addition to carry-on baggage so if you do have bigger paper, you can probably just stick it in a plastic bag and carry it that way.
Mailing it home is also a good idea.
I'd be nervous about checking the paper because, as mentioned, an inspector could open it. Also, the CT scanners they use on checked baggage have a much higher probability of causing fogging than the x-ray machines for carry-on baggage. Film can survive x-rays but will be destroyed by CT scanning; I can't help but think that photographic paper, although slower, would fog at least a little.