The chemical equation in the off-network marketplace is just about perfect for Warner Bros. Domestic TV Distribution as it preps for what is sure to be a megabucks sale of rerun rights to CBS laffer “The Big Bang Theory.”

The timing of the sale — expected to happen within the next two months — and the competitive dynamic among the likely TV station and cabler bidders adds up to a deal that could yield as much, if not more, than the estimated $4 million per episode in off-net coin that Warner Bros. is raking in from “Big Bang’s” Eye skedmate “Two and a Half Men,” which bowed in syndication in the fall of 2007.

The two key station groups for off-network sales, Fox Television Stations and Tribune Broadcasting, have strong incentives, for different reasons, to bid aggressively for “Big Bang.” At least four major cable players — including TBS and FX — are expected to be contenders for the CBS/Warner Bros. TV laffer, co-created and exec produced by Chuck Lorre and Bill Prady.

Demand for “Big Bang” has been stoked in part by the boffo syndie performance of “Men,” which also hails from the Lorre laugh factory. But first and foremost, “Big Bang” has heat because it is that most rare commodity in broadcast TV: a hit sitcom with a growing aud. Moreover, “Big Bang,” which revolves around a group of misfit geniuses who befriend their sexy femme neighbor, is much in the “Men” mold in that it has a strong male following, a syndie-friendly multicamera format and a broad kind of evergreen humor that has traditionally done well for stations in Monday-Friday plays.

“Big Bang” is close to wrapping its third season with a 41% gain over its sophomore year in total viewers (14.3 million) and a 39% hike in adults 18-49 (5.3 rating). It got a big leg up in moving to the post-“Men” 9:30 p.m. slot last fall, but it is hardly a lead-in driven success story. “Big Bang” typically builds on the demo perf of “Two and a Half Men,” making it primetime’s top laffer in adults 18-49. (“Men” still reigns in total viewers.) For Warner Bros.’ syndie wing, there’s no better sales pitch than those stats.

WB is expected to formally begin pitching the show to TV station and cable buyers in May or early June at the latest for a fall 2011 start. The prospect of the show going on the auction block has been a hot topic of conversation among buyers for months, ever since Warner Bros. let it be known that the sale process would begin in the spring.

The big question among buyers is how the “Big Bang” off-net deal will be structured, and whether the cable window on the reruns will begin in 2011 or be delayed to give stations a year or two of exclusivity.

Reps for Warner Bros. Domestic TV Distribution declined comment Thursday.

There had been chatter that a cabler might seek to up-end industry precedent by grabbing the show exclusively for cable runs at the outset of its off-net run. But under that scenario, it would have to pay more than $3 million per episode to make it worth Warner’s while to not sell the show on a market-by-market basis to local stations. The highest price a cabler has paid for an off-net comedy to date is the roughly $800,000 per seg that FX has shelled out for “Men” rights, which kick in this fall.

Industry insiders say the timing of the cable window will depend on how much local stations are willing to pay for the show. If the stations dig deep and commit to license fees that surpass what Warner Bros. secured more than four years ago for “Men,” the distrib might be inclined to hold off, as it did in implementing a three-year delay for the cable window on “Men.”

But more likely, observers say, “Big Bang” will go to broadcast and cable simultaneously in 2011. Local stations are just now starting to see the start of a recovery in an ad market that plummeted by double digits during the past two years. Although the scarcity of a hit sitcom makes “Big Bang” somewhat recession proof, the revenue hit that stations have endured will still put a brake on the kind of wild bidding from stations that syndie distribs with hot properties enjoyed in the go-go 1980s and ’90s.

In 2006, Tribune-owned stations in New York, Los Angeles, Chicago and other top markets committed huge dollars to grab “Men.” It was a gamble that has paid off. The show’s success as the top-rated off-net sitcom by a mile been has been credited with keeping the troubled Tribune Co. empire afloat even amid bankruptcy proceedings, and with allowing Tribune stations to dominate its Fox O&O rivals in the important pre-primetime 7-8 p.m. hour.

With “Big Bang” coming on the market, Tribune is sure to make a big play for the show, but so is Fox, after missing out on the “Men” juggernaut. On the cable side, TBS is seen as the most aggressive bidder because the channel that styles itself as a comedy haven is in need of a strong off-net property. But FX also has incentive to grab it as a companion to “Men.” USA and Comedy Central are also known to have expressed interest, though it’s unclear how aggressively they will bid especially if the pricetag tops $1 million, as some syndie vets predict it will.

For Warner Bros., the biggest component of the “Men” payday has been the barter advertising time that it receives from local stations. The three 30-second spots it gets in every syndie airing of “Men” yields the studio an estimated $80 million a year in national ad sales. And that number will only increase once the FX telecasts begin this fall (in which Warner Bros. also receives the same 90 seconds of barter time).

All of this makes the syndie calculus for “Big Bang” very promising indeed.