Well, it's like anything else, numbers matter. If the vendors of some of the IC's sold here were promised 1000 unit sales, or 10,000, then prices would drop dramatically. It take a considerable amount of time and $$ to build a custom piece, assure the quality, source the parts and production and sell them.
Look at exhausts too..most of them are 2 cans and some piping and still cost $1500-$2000. But with so many for sale, what can a one of these vendors hope to sell over a couple year period? 100? 200? All the costs to that go into it attribute to the cost of each unit. That's why there are usually such dramatic pricing drops for group buys, even when they are only 30-40 units.