One of the most common ways to interface a computer and custom electronics is still a serial port. Since 9-pin connectors are mostly thing of the past usual choice these days is an USB to serial bridge chip.
I went forward only to be surprised at the shipping cost for a device that cannot be heavier than a few dekagrams. Cheapest shipping within United States was $26 - a way too much for this device especially when anyone, as a private person, can get a better deal from UPS. How come that company such as Silicon Labs cannot ship it cheaper? Answer is - they can.
Over-inflating shipping cost became popular on ebay as a way to seem really cheap. You decrease item cost and increase the shipping. Total amount you get is still the same but your offer stands out as the cheapest one. With time this way of pricing has spread to Amazon and essentially any site that allows you to set shipping cost.
Somebody from Silicon Labs wanted to be able to say they do cheap kits but without all the hurdle of actually being cheap. I call that lying, they call it marketing. :)