If you manage to find cheaper than Kaihung mats then please do check with the supplier what the density is (if in doubt ask for a sample).

What is 35-45 hardness?
EVA mats can be made to any firmness, i.e very soft for childrens playing areas to very hard, for example a free weights area.
The standard hardness for martial arts mats is 35-45 degrees.
This measurement is not a sign of quality, just the firmness of the mat. (35 degrees is slightly softer than 45 degrees)