HDMI transmit a DIGITAL signal. It's not like the old Analog ones, where the quality of the cable really played a role.
It's simply 1's and 0's. As long as the connection on the other end can tell if it's a 1 or 0, then the "quality" of the cable really doesn't mean anything.
If anyone "swears I got a better picture" using a Monster or any of those other overpriced cables, they're simply not educated on how it works. I've got a degree in Electrical Engineering, and trust me, people are seriously misguided on these issues with HDMI cables quality.
The only thing an "expensive" cable can help you with is signal loss over distance. Say if you were running an HDMI cable 20+ feet. That's the only case where it would help any.
In short, don't be scared to buy a cheap HDMI cable for short runs.
I will have to agree, an HDMI cable is an HDMI cable is an HDMI cable, however I have come across a few "bad" cables.
It happens, had a cheap cable fail on me. The failure was quite odd, some of the picture on the screen was actually distorted and jumping (only certian horizontal lines), changed the cable and it was fine- was indeed quite odd, but for under 5.00, it was cheap enough to replace!