Then don't buy one. Problem solved.
The fact is that Apple followed the same practice as earlier phones. Good, Better, Best. Each year, there's a new Best and the previous Best drops to Better. The only difference this year is that the new Better is not exactly the same as the previous Best - it has a new case, and somewhat improved internals. Unless you're working in Apple's finance department, you have no idea what the cost difference is. In the end, they decided that the added features (better camera, color, and other improvements) justified keeping the price the same.
Not to mention, of course, that price is not determined by manufacturing cost, but rather by what the market will pay for an item. Even the most pessimistic reports are that Apple sold 2 M of the 5C model on opening weekend - which is probably the best launch ever for a phone using year old technology.
Nonsense. People offer promotions for all sorts of reasons. One of the big ones is simply to get people into the story.
Think about Black Friday. It's quite common for companies to offer products at huge discounts in very limited quantities - simply to drive store traffic. Heck, there were companies offering discounts on the Wii back when they were in incredibly short supply everywhere. And, as someone pointed out above, Walmart announced discounts on the 5C before it even launched, so your premise is flawed.
We don't know that for sure since there are no actual figures. However, when even the most pessimistic estimates put 5C sales at 2 M in its first weekend, it's likely to be selling well.