Watercolor blocks are expensive...So ...
(Emily, MN USA)
Make your own!
Buy a tablet of W/C paper and glue the edges with rubber cement leaving only about one inch on one edge which allows you to remove the sheet easily after you have painted it. I did it and it works like a charm. You can also use the Masking liquid to glue the sheets together along the edges.
You can make tablets of your favorite sizes by cutting them to suit yourself. This really works wonderfully.