If your just going to do a one off then stay away from the jets. here is an article of a block made by a forum member at
www.overclockers.com. It is similar to a Rotor block and it's performance is up there with the best blocks on the market. best of all it was made with a drill press and dremel.
http://www.overclockers.com/articles690/
That is the kind I would suggest for a " do it once, and do it well" type of block because it is pretty much garanteed to work well on the first try as opposed to the Jet version that are not. The one in the article looks a little "getto" but it works damn good and the looks can be improved. This is a similar block to what I plan on milling in the next few months. Have a lot more CAD work to do but hope to have it done by the time pH starts testing DIY blocks.