So, I decided to make my own. Postcards are basically just heavier paper cut to a certain size. I've seen some creative ideas on Pinterest using cereal boxes. However, I wanted more room to write on my postcards.
So I bought a package of card stock on Amazon. (I'm confident you could find paper local, but I live in the country and utilize Amazon Prime regularly). The paper was $12.95 for 50 sheets of 100lb extra thick white card stock. Each sheet makes 4 postcards. So for a little work I got $200.00 postcards for $12.95.
Once I had my paper in hand, I tried to print on it. My ancient printer wouldn't feed the paper. So I decided I could hand decorate the postcards instead of print on them. So, I first measured out the size of the postcards. Standard postcard size is 3.5 inches to 4.25 inches high and 6 to 6 inches long. Postcards need to be approximately 0.007 and 0.016 inches thick. Obviously thicker postcards are less likely to be eaten by the postal sortation machines.
Once I had measured everything out, I used a paper cutter to cut the the card stock into the correct size. I used a ruler to make the line on the back where you put the address . Finally I did a small decoration on the front. Something to keep in mind is the bar code sticker may go along the bottom or top (they don't always end up on the back), so you might want to move your decoration away from the edges.