I have also given this some thought. We play a lot of steel tip darts around here. Yet I like the idea of the game doing all the work in regards to counculations of score for some of the strang games like SPLAT. I want one with the 13" video screen. You can buy most of the parts online but I dont know how to hook up the tv and computer that runs it.
I think that the one you posted is just a top of the line wall hanging model set inside a cabinet. I think the unit itself is about $300.00 I even think it talks and has a heckler mode just to tick you off. Building this cab would be a snap. but one with the tv and cpu to run it would be a little tricky unless somone on this site has some ideas.