Regarding people guessing $40 for individual joycons, I can see where they're coming from--it's the price wiimotes went for, so there's a precedent for what the sort-of-half-controller goes for. Personally I don't think the standard joycons will be sold individually, at least outside of Nintendo's online store.
$40 makes sense but it does suck.
I expect we don't see variants for a few months at least after launch. Their big thing will be to get as many systems out there as possible.