DVI signal's start deteriorating after 30 feet I believe. I have never personally tested it, so I don't know for sure.

Also, HDMI is basically a brand new cable, so prices will probaly be high until more manufacturers start mass producing the cables. Why dont you run a 2" conduit from your rack to where the TV will be so you can add whatever cables you need when the time comes and you won't have to hire somebody to do it for you each time you run a new cable?