I'm sure you hard-core DIYers have already seen this site, but I recently stumbled across it and find it amazingly cool. http://www.mcmaster.com/
they have an amazing array of parts & equipment, from 3-pc SS ball valves to rollers (DIY grain mill?) to temperature probes to heating elements. The prices on a few things like the ball valves are lower than at northern brewer.
I just wasted about 2 hours browsing. enjoy