OT: How best to record "off-the-air" HD-TV?

[Josef Lowder]

.
This might not be OT if there is a way to use a Linux computer 
to do what I want to do. 

Being fed up with cable/dish gouging and being force-fed 100+
garbage channels that we *do not* want, a few months ago,
we switched to just viewing "off-the-air" TV.  The HD signal 
is so fabulous that we don't even watch anything that is not HD. 

The one problem, however, is that I have been told there is no
way to record HD (and other digital) channels from "off-the-air" 
broadcast; and that the only way record HD-TV is with a Tivo and 
being forced to pay a monthly subscription fee? 

Is this true, or are there any other HD-recording products 
available and some other way to record HD programs "off-the-air"? 

Searching the 'net, I found that there used to be a Sony HD-DVR 
that could record HD "off-the-air" but it was a very costly 
product and is no longer available unless you can find a used 
one on ebay. 

Are there any other options?