you can run them I'm sure mine is around that length although I probably woudn't buy cheap.

My plan is to get a amplifier with HDMI outputs so that I can plug all my equipment into that and then just have one hdmi cable going to the plasma.

Also could you not get some tubing that you can put into the wall which you run the cables through, that way if you need to replace or upgrade a cable all you need to do is pull the new one through with string.