IME a good quality HDMI cable is well worth the money...although I don't have a ton of experience.
I had originally bought a cheap $40 one from Home Depot (I think) and really was not impressed. I ended up getting a "high end" one from Best Buy (you don't want to know how much
) and I notice a huge difference. I don't think I needed to spend so much but I would recommend doing your research (as you are) and getting a good HDMI cable at least.