Heidi Montag and Spencer Pratt might be running the most lucrative faux celebrity relationship in Hollywood. Not only are they said to be pocketing cash for cooperating with photo agencies like Pacific Coast News, but we’re also hearing they’re under the sheets with the celebrity weeklies.

A tabloid operative with direct knowledge of the situation insists Us Weekly paid the couple a “HUGE fee, around $15,000″ in exchange for shooting them for the “Why I Called Off My Wedding” cover story.

It’s on the books as a “location fee,” we’re told, which would allow Us to hold up its public persona of not paying for stories or access, while getting the shoot through accounting’s spreadsheets.

An Us Weekly top editor, who spoke on the condition of anonymity, flatly denies the charge: “No, we didn’t” pay, says the staffer. “Make-up was taken care of by us,” but there weren’t even any travel incidentals to pay for, since “I think we shot at his house.”

Which is true; the photos were taken at Spencer’s house in the Palisades. (Wenner’s money managers might be wise, then, to question any such “location fee.”) And it’s also a little perplexing that any magazine would have to pay to shoot Heidi and Spencer — those two will sell their first through fifth born for a cover, or even a quarter-second of footage on a VH1 countdown show. But that’s the rub.