I did some research on reasonable prints and found that some services are pretty good and fairly reasonable. I ordered two prints from pixels.com and they really impressed me.
This one is the art I did for the cover of Winds of the Ice Forest. It is printed on heavy watercolor style paper. These prints are archival and have something like a 50 year guarantee against fading. They were shipped as rolled prints and I put them under a heavy book for a couple of months. So I signed this one and I plan to get a frame for it.
The other one is The Rat Queen Dies Tonight map from Black Pudding #5. This one is also on archival paper, but it's more of a bristol type. Like a heavy cardstock, smooth.
For this print I plan to color it by hand and then frame it. I think that would be a really fun way to create some interesting tangible art (most of my work is digital, you know).
I have no idea how to market these things. I suppose for now I'm just going to put them out there and see if there is any interest. If you like collecting originals and/or prints let me know what you think.