GIK Acoustics has a lot of affordable products. So does Realtraps (a little more expensive). And there is extensive discussion of DIY basstraps on some of the other forums that are more devoted to in-depth technical discussion of home theater.
One of the pictures was of your subwoofer, sitting in the corner. Is that where you have it at present? While perhaps not always the case, placement of a subwoofer close to a wall, or especially close to a corner tends to make the bass increased-some characterize it as "boomey". If you haven't done so already, you might want to consider changing the position of your subwoofer. Doing a "sub-crawl" by putting the subwoofer in your preferred listening position, and then crawling around the room while listening to something with lots of low end can give you an indication of the best place to position your subwoofer.
You may have already tried this. Then again, you may have been more like me. The idea appealed to me, but I got two subs (Epik Empires). Those things were heavy. I did some reading on dual sub placement, and tried them at the midpoint, along two opposite walls. Even so, I found had had a rattling and booming sound with one close to the wall that was covered in stone, and had to play around with position a bit. I also experimented a bit with using one subwoofer, and found that two gave me more even sound in different areas at the same time than either one alone.
If you haven't tried changing the position of your subwoofer, you may want to before trying bass traps.