an LNB (the thing that goes in the focus of a parabolic antena) is really cheap and easy to power
the probem would be that the cheap dtv (RTL-SDR) only gets up to 2.4MHz of spectrum bandwith, a typical DVB-S mux can be around 20MHz or the DVB-T terrestrial standard, 8MHz
Not everything prepper-like is for prepper-only usage