That's how it goes with keyboard kits
So here's another thing to keep in mind (not justifying costs or anything, but explaining) -- a lot of times these kits are sold in small quantities. They might make 300, or 500, or 1000. A company like Logitech or Razer might make 50,000 on their first run of a new keyboard (just a guess, I have no idea). Since there are so few people, everyone shares the cost of manufacturing. So, they're more expensive because there is no big corporation with existing tooling to actually make it.
Switches and keycaps aren't included, as weird as it may seem, because a lot of enthusiasts want to choose their own. If they were included, the cost of the kit would be even higher!
With that in mind, you can totally find custom kits for $100-200. I reviewed one here that actually does have switches and keycaps for $169, IIRC. RAMA Works keyboards are pretty swank, so they're quite a bit more expensive.