Oh yeah, you're right, they're not so hard to make, specially considering the uber-complexity of graphic chips nowadays. the only thing is that albeit they are people willing to sacrifice a significant number of small animals just to be able to buy one, those people are still a bunch of, say, 1000. And I'm feeling optimistic here ; Not worth even remembering what a SD is, and what it exactly does.
And yes, external SDs are basically pieces of junk. All details are on amidude thread, mentioned earlier.