I ought to mention American Gunsmithing Institute (AGI), too, as they do offer a video course, which is conducted mainly by Bob Dunlap. I have watched, pretty much, the entire course. They cover things that a correspondence course does not cover, or cover well, and I didn't care for the hot caustic bluing video. They use a different system to Brownell's Oxynate 7.
What they do show, that is good is:
Heat treating and case hardening (a must)
Assembly/disassembly/operation using cut away guns
Hot water bluing
Sear systems (a must)
Rebarreling/chambering/headspace (another must)
Bedding a stock (by Darrel Holland)
Plus, they have a machine shop and welding course video.
If you can find this as a used course, it will be very much cheaper, but you will not be able to take the exams, nor get a diploma that way. However, it would be good to compliment a correspondence course with.