I've built a fusor while in high school (a couple of years ago), and it's certainly within the reach of a dedicated person, or somebody with lots of support.
More info for the interested at http://stores.lulu.com/raymondj
For me the fusor wasn't really an end so much as a starting point: it is an educational experience that is unmatched, because to build a fusor, you've got to have a grasp of high voltage, high vacuum, and gas management systems. Learning about these things in theory is nice, but there is nothing that can compare to slaving over a hot wrench after bolting down your chamber for the last hour and leak checking every single seal.
And, if anything, it does look good on a resume.
Life would be so much easier if we could just look at the source code. -- Dave Olson