Don't get me wrong either. I'm just pointing out that the same technology as in an ObiWiFi can be had for considerably less than $20. There is nothing extra in the OBi version that costs significantly more to produce.
Of course price often has little relation to cost. For example, think of car spares and compare prices for identical parts for say a Ford and a Mercedes. They may have been sourced from the same manufacturer and be absolutely identical apart from marking with a Ford or Mercedes logo and part number. Same specification, same quality but I doubt you'll see the same price for that item on the bill when a Ford mechanic fits a Ford one and a Mercedes mechanic fits a Mercedes one.
While $20 for an OBiWiFI may seem reasonable, in comparison to the electronics that is in one of their ATAs at the prices they are, an OBiWiFi is expensive. And the NRE cost that needs to be recovered in each ATA sold is way, way more than for the OBiWiFi.
Having said all that, I'm not accusing Obihai of having their customers over a barrel and ripping them off. (Just don't mention a certain fruity company!)