I know Sun sells CBT versions of many of their training courses. I used them when preparing for my certification tests. But they are terribly expensive so I only got to use them because my company had a set.
Also, I have a set of 7 CBTs I bought back in 98 or so which cover Unix usage, administration, shell scripting, and networking. I was a helpdesk guy who wanted to be a Unix admin instead. The Unix manager had me talk to some of the admins and figure out a training program. We found these from a company called National Education Training Group. They were decent, but a little basic. Even with just my helpdesk experience I knew maybe half of what was on the CBTs. Great for somebody just starting out, but not if you have much Unix experience at all. I think NETG is still around but I haven't looked at their site for a year or two.
It worked though. . . That manager offered me a job at the next company he worked for and I've been doing Unix admin ever since. The CBTs are still sitting around on my desk waiting for me to get the ambition to put them on ebay.