Oracle, your post begs the question: how are prices of $5 for the PCB and $28 for the kit "so high compared to what the the parts and small PCB are worth"? I assume there's a markup to cover the time spent packaging kits and processing and shipping orders, and that doing the math would boil down to minimum wage or less for the dedicated RRRF folks...
The 2 driver ICs are $10 combined (which I admit is a lot higher than I'd thought). But the PCB should be under $2 (Golden Phoenix 155 square inch special for example), and a handful of support components. It probably costs them $15 total.
At that price, maybe $28 is reasonable, as I said I thought the chips were a lot cheaper.