They do exist. I have one in my computer.
I have seen them as low as $15 and on up to over $1000.
Depends mostly on what features you want with it.

Mine is just a PCI card that plugs into the motherboard.
Then I can hook up TV cables to the back of my computer.
And I can watch TV on my computer.
If I ever get another one I will get one with TV OUT
so I can output video to a regular TV screen or VCR.

What will be the source of the video you will be recieving.

Try the link below.

You will need a computer to go with the monitor,
but you can use some fairly low end computers.
Something old and slow, in the 500mhz range would work.
Maybe even slower, down into the 400mhz range.

If you want to record video on the computer then
you would need a fast computer and fast hard drives.
But for just watching TV you can get by on an old one.

For real reviews from real people/users
you can look up a particular device here.

Hope this helps.

Pooh Bear

Here is a link that might be useful: NewEgg.com TV Tuners

Thank you for the reply.

I should have been more clear. I don't intend in hauling my PC with us in the trailer. If I was willing to do that I'd just get a cheap CRT TV and be done with it. I am looking for a stand alone tuner to plug antenna or cable into and output to an LCD monitor display and separate sound system.