I don't think it's on TV anymore (and if it is, it's only on really early in the morning on saturdays or something like that), but you can get them on the internet now. There is a site that is set up to distribute and preserve old TV shows like that, it's called DAP Central (DAP stands for Digital Archive Project).
There used to be a big comunity of fans of the show that traded and swapped taped episodes, but now they just do it all over the net with file sharing programs.
They only share episodes that are not commercially available for sale (they say that's how they stay comfortably in the gray of copyright:) ), but there are still like 200 episodes available through the DAP.
Are there any other DAPers out there? I have been going to the site for a while, but I've only been able to get about 150 Episodes of MST3K (they use a buggy file sharing program called e-donkey that is very sensitive, and when I upgraded to the latest version it stopped working for me).
You should check out the dap, it's address is http://dapcentral.org. They do other tv shows like News Radio (I have all of those), The Critic (I have about 20 of those), and a bunch of other shows like that. You can put your suggestions into their board for other shows that you would like to see "DAPed" (or "preserved digitally").