ereaderiq used to be a good website to find freebies, but I think Amazon might have stopped them. However, they link to another website where you can browse freebies by genre. It has horror, but not thriller, although it has 'Men's adventure' not quite sure what that is. Here is the link anyway:
Has anyone read any good ones? looking for cheap reading material but am having trouble finding ones that don't seem awful, there seems to be a lot of romancey/fifty shades of grey types which wouldn't be my bag. I'm more of a thrillers/horror reader.