What’s happened to good TV on Saturday nights?

The state of network television on Saturday nights has become so dire that ABC has essentially put a prime-time slot up for auction to anyone who has a compelling idea – as long as it’s done very cheaply.

ABC has put the word out to Hollywood producers that a Saturday night home is available to a program that can be made for no more than $500,000 an episode, which is about a quarter of what the traditional comedy or drama costs.

Saturday has become the forgotten night for broadcasters, who aren’t entirely sure what to do there anymore. They just know it’s not worth spending much to seek an audience that clearly has other plans.

Since 2000, Saturday night network TV viewership has dropped 39 percent, according to Nielsen Media Research.

Except for occasional specials, CBS’ “48 Hours Mysteries” is the only original Saturday night program on the original Big Three networks this season. It’s preceded by two hours of reruns of procedural dramas called “Crimetime Saturday.”

NBC has found Saturday to be a comfortable home for its “Law & Order” franchise and also is using the night to give viewers a second chance to catch on with its new series. A week ago, the network ran three straight episodes of “My Name is Earl,” and has also showcased “Surface.”

For the past few weeks, ABC has given fans of “Lost” a second chance to keep up with that story. It has also aired repeats of “Invasion” and “Commander in Chief.”

Fox has run “COPS” and “America’s Most Wanted” on Saturday for years; the WB and UPN don’t broadcast.

Viewers with long memories know it wasn’t always this way. “Gunsmoke,” “Perry Mason,” “Mission: Impossible,” “Love Boat,” “Fantasy Island,” “Golden Girls” and “Touched By an Angel” are among the classic series shown on Saturdays.

You could make a strong argument that during the early 1970s, CBS on Saturday night had the single best night of prime-time TV ever: “All in the Family,” “M*A*S*H,” “The Mary Tyler Moore Show,” “The Bob Newhart Show” and “The Carol Burnett Show.”

The decline in Saturday viewership caught momentum with the advent of cable television, particularly when HBO scheduled its showcase movies then. The popularity of home videos and DVDs gave viewers still more options.

It’s become a classic chicken-or-egg argument: Are the viewers fleeing because the networks aren’t offering much, or are the networks abandoning Saturdays because they sense viewers’ lack of interest?

Experimentation, along the lines of what ABC is planning, might be the answer. Why can’t the networks try out pilots of new shows, even ones executives have rejected, to see if something draws some interest?

ABC has set no boundaries for the suggestions it seeks: the shows could be reality, scripted, news, sports, whatever, said Jeff Bader, the network’s head of scheduling.

“We use the summer to experiment,” Bader said. “Well, Saturday can be our summer every week.”