Word of caution if you want to make a wool pressing mat. Make sure the wool you use is 100% wool. A friend encountered an issue when purchasing a product labeled "wool felt". It scorched because it had some man-made fiber in it.
I see online the wool pad mentioned above is $55 or more.
If army blankets are not available, I wonder if you could get some mill ends/irregular wool pieces from woolen mills to make your own?