With the wicked cost of credit and lofty mortagage rates knocking $1,000 to $1,500 off the price of many homes in recent months, it's fair to speculate that we may finally be reaching the upper limits of how high real estate can go.

Don't try selling that argument to Jody Sherman; she'll tell you you're crazy. Her view: If you charge astronomical prices, offer the ultimate in luxury and house people in a veritable marble fortress where no mugger or fire can get at them, the sky's the limit.

The pert, blond 36-year-old ought to know what she's talking about. She owns 51 percent of the nation's (and Maybe the world's) single most expensive complex of condominiums. It's called the Wilshire House in (you guessed it) California. And based on her ability to fetch unbelievably high prices for her opulent housing units -- up to $11 million, would you believe -- Sherman's going national.

She's taking her act to New York, Chicago, San Francisco and maybe Houston. And that's for starters.

Her piece de resistance: a $20 million penthouse -- your own castle in the sky.

It'll be one of some 35 to 70 units, the ultimate condominium, all housed in a single complex. And the starting price (for two bedroms): $1 million.

As Sherman explains it: "Who cares what we spend;" our customer wants the best, and price is no object."

If you think this is all pie in the sky, think again. Sherman's not only a talker; she's a doer.

Born into a family of modest means -- her father was a grocer in Manhattan's Little Italy, and she grew up in $85-a-month apartment in Brooklyn -- Sherman has parlayed a knowledge of real estate (first selling, then developing) into a personal net worth of about $11 million. A big plus, of course, was the exploding price of California real esate. And then there was her marriage some 10 years ago, her second, to Earl Sherman, a prominent Los Angeles real estate developer and contractor.

But it was Jody, a one-time movie and TV actress, who made her mark on California real estate by taking foreclosed buildings, giving them "plenty of loving care" (new management, creative advertising and substantial face-lifting) and transforming them into profit-producers. And it was Jody, again on her own, who sold $75 million worth of income-producing real estate (both residential and commercial) between 1964 and 1966.

I caught up with the fast-stepping real estate developer in new York the other week; she was in town to talk to the folks at Irving Trust Co., one of her bankers, about arranging the financing to bring the Wilshire House concept to New york. She got the green light, she tells me, and a feasibility study now is being arranged to determine location, the size of the rooms and specific prices.

Plans are presently being formulated for the openings of other locations, as well.

What, you may wonder, is the ultimate condominium?

For an answer, let's look at the roughly $140 million Wilshire House, a sprawling 67-unit, 21-story building in Los Angeles' posh Westwood Village area. Of the 67 units, which currently range in price from $1.5 million to $11 million, 54 already have been purchased; all but two of the buyers are Americans. Of the two $11 million penthouses, one already has been spoken for a by a retired chief executive of a publicly owned company.

Assuming that all units are sold (sales officially started last August), Sherman personally will clear a profit, she tells me, of somewhat between $13 million and $25 million. An amount close to that would also go to her 49 percent partner (a private investor).

The grand penthouse -- the one going for $11 million at the Wilshire, but which Sherman figures has to go to roughly $20 million to factor in full inflation several years out -- is just about everybody's dream. Embracing 7,000 square feet, it has five bedrooms (more if you want), 40-foot gallery entry halls, 8 1/2 baths, a 20-foot glass enclosed solarium, three fireplaces, garden terraces off all rooms, a private screening room, saunas, a wine cellar, vault and, if you want one, a free Rolls-Royce (you pick the model) with personalized license plates.

Like to get about town quickly? Tht's possible too -- thanks to the helicopter on the roof.

But the big story, aside from all the luxurious touches, is the security: virtually complete insulation against fire or theft.

Sherman has spent more than $5 million to prevent each with what she says is "the ultimate" protection.

Sherman recalls that she was nearly raped at the age of 17 and says this heightened her consciousness of security. And so, among other things, the Wilshire house maintains a staff of armed guards, essentially off-duty policemen, who, she tells me, "are prepared to kill." Adds Sherman: "The place is like a fortress; you couldn't be more secure if you had a moat around it."

But let's say you get past the security force and make it into the elevator; aren't the occupants vulnerable, I asked.

Allowances have been made for that. Sherman says there's no way you could get into any apartment on your own since the elevator buttons have to be activated by either the security guard or the occupant to permit the elevator doors to open on a given floor.

But if all else fails, she tells me, there're the "panic buttons" located throughout the apartments (in fact, you can even keep one on your person) Just a simple touch -- the buttons operte through a short-wave system -- and the guards come running.

To protect against fire, uppermost in the minds of a lot of people, considering what happened at the Hilton and MGM hotels, the Wilshire House has sprinkler systems concealed in the ceilings. Any problems and, pow, you can be an immediate rainmaker in your home. There're also fireproof service corridors on each floor, smoke detectors and that helicopter to help you off the roof if things get out of hand.

"The chances of burning to death are nil," says Jody, "unless you decide to set yourself on fire."

With all the protective devices and luxuries, isn't there a point, I asked, where costs get so out of hand that there will be no market for these super-plush bunkers?

"Impossible," she responds. "There's no shortage of rich people. What we're offering is an extension of a lifesytle for people who want the ultimate in privacy and security. what are they supposed to do -- go bargain-hunting for something that could save their life?"