I just ordered my postcards for the 2017 Liberate Your Art Postcard Exchange happening in March.
I tried printing them myself on my home printer, but the quality is just not the same -- and it kind of defeats one of the purposes of the project which is to print your art, and get it out into the world. Having them professionally printed add a level of legitimacy and professionalism that just can't be beat -- provided you've got good stuff to start with. ;-)
I've been using Moo.com for professional printing. And they do a nice job! At present, they are offering 15% off of postcard sets. With shipping, I'm paying about $1.30 / postcard and I get to use my own designs.
I will have extras, so if you like what you see, join us! I'm also open to side swaps--so if you don't get one of my cards in the official exchange, contact me about a side swap. There are several people I keep swapping with every year, just because I met them through this artful exchange.