I use a JVC Everio camera for fimling ELR. It has 40x optical zoom, and a very nice 100x digital zoom. You can zoom 1000x digital, but the quality is very poor.
It cost me 300 usd here in Norway, I bet it is way cheaper in the US.
My worst struggle with this camera, is that when Auto focus is enabled, it reacts to mirage at high zoom, so the picture suddenly goes blurry. When I shift to manual focus, it is mch better, but it is very hard to see when the pic is very crisp in that small LCD screen. But filming hits a 2 km is no problem.
Here is a video I did, shooting my 338LM at 1953 meters, at a rock face. If there had been a milk jug up there, it would have been easy to see it.
I have also bough an adapter, so I can film through my spotting scope. I'll link a video of that in here too
The rock is more than 2500 meters away, and the mountain top is more than 3000 meters away.