The antenna is cheap, but that's not the whole cost. You need the 8VSB reception stage, and then a slice of a server to transcode that 8VSB into H.264 or whatever format they chose. Then you also need disk space for the DVR stuff.

It's not the array of antennas that boggled me the most, it was the racks and racks of servers encoding the exact same show hundreds or thousands of times in parallel.

They look like unbent paperclips sticking out of a pcb.