There are so many variables, but the thing that can make or break the concept is the tower rent. Some rural markets are quite reasonable, like $400/mo. I once worked on an LPTV project in a rural market, but all the towers were owned or managed by the same company, so it was about $2000/mo, plus hefty start up costs around $50,000. And that was for a single antenna at the 100 foot level serving less than 20,000 people. It killed the project.
As far as hardware, it's getting more affordable by the day. The line between consumer and professional grades is blurred, you can really handle much of the video digitally and easily stay way below $10,000 (video part only). There's a list of equipment that is codified by law that you must choose from, like the EAS encoder/decoder and RF Amplifier. But the rest you can be creative with. You need broadcast grade cable and should use an antenna that is listed on the FCC's "Off The Shelf" antenna list.
I built a tiny (licensed) LPTV station on someone's property very much on the cheap. Video source was a Windows 10 tablet. Included ATSC encoder, EAS, 1 watt transmitter and a parabolic Kathrein Scala antenna on a short pole pointed towards the population. Probably spent $15,000. It was on a tiny solar array with lots of second hand parts. It was a ridiculous amount of fun. And it was mind blowing that I was able to receive it 10+ miles away for so little cost.
PS: I don't recommend using a Windows 10 tablet as a video source. It's comical how may things can go wrong (i.e., notifications automatically turn back on; someone reorients the tablet on a table and your station is suddenly in portrait mode; etc)
