Welcome to the boards, Bev!
A lot of people take advantage of the SBI! $100 specials to either buy a second site for themselves or split the cost with someone else.
There are two successful computer-related SBI! sites that I know of. One is
www.updatexp.com and the other is
www.cheap-computers-guide.com. So if this is really your son's passion then he can certainly find success with this niche.
The bottom line is you can create a successful site on any niche as long as you have the passion and some creativity to make the site stand out. The problem people run into is when they choose topics because they see others succeeding with them. Then what happens is they lose interest and don't get beyond 3-4 pages because it's not something they really love. Or they end up copying what's already out there and it fails to draw any attention because it's just a copycat site.
But if computers is really his passion, I say go for it!