I have 10m run to my projector via $30 (second hand off trademe) dick smith cable. It's pretty thick, has nice shiny gold ends, but more importantly it works great. If it didn't work great I'd have to look at an inline amp, or a better cable.
I also have a 10mtr dick smith (purple colour really chunky) only problem is that it wouldnt do HDCP from myskyHDi to either my projector or LCD so i had to replace it.
I currently have 2 cables from Rapoloav 1x15mtr and 1x10mtr connected via a splitter to my receiver which is feed by HTPC and MyskyHDi. Not the cheapest cables but as I was at the 10mtr point I didnt want to go to cheap - especially after the HDCP issue on the dickies cable. Think I paid about $120 for 15mtr?