North Shore's aura of exclusivity keeps home prices high in the area.

When you get beyond the renovated brick factories of Lynn, up toward the Marblehead boutiques and beyond, those on the North Shore show a certain elevated-nose, poised-pinky attitude about South Shore real estate. Comparisons are somewhat haughtily brushed aside.

''Well, we don't have the Southeast Expressway.''

''I don't think they play polo on the South Shore, do they?''

Indeed.

In the late 1800s, the wealthy Boston Brahmins moved here, settling in estates befitting their social stature. While many have moved on, their legacy is ''a life style,'' explains Richard Carlson, president of Carlson Real Estate, the largest Realtor on the North Shore.

And that life style fetches higher home prices. ''The average selling price is $93,000 - and rising,'' says Christine M. Todd, executive vice-president of the Greater Salem Board of Realtors. ''But that takes in Lynn, with its entry-level $75,000 to 80,000 prices, as well as Swampscott at about $120,000,'' she adds. It doesn't include Manchester-by-the-Sea, where many homes are exclusive members of the $350,000-and-up club.

Shoppers for an upper-income home can find it along the coast and further from Boston, say Realtors. ''Trade-up'' homes (priced higher than $120,000) are most abundant in Marblehead, Swampscott, Topsfield, Rockport, Hamilton (home of the Myopia Hunt Club and the National Equestrian team), Wenham, and parts of Beverly. Inland, Lynnfield has a reputation of being a bedroom community of professional athletes. Homes in this rural community are generally pegged at $ 130,000 and up.

Coming down to earth a bit, houses in Stoneham run about $100,000, although there are ''nine or 10'' condominium developments where resale figures run $75, 000 to $80,000, says Laura Hogan of Realty World Schmid Real Estate.

Stoneham lacks local public transportation, and that's one reason why nearby Melrose, Wakefield, and Reading have ''slightly higher'' prices, notes Mrs. Hogan. Unlike Stoneham, Melrose is strictly residential; it has no industry and is well endowed with Victorian homes. Peabody, Saugus, and Danvers also have an inventory of mid-priced houses.

In the market for a starter home? Brokers suggest Malden, Revere, Saugus, and Lynn. A single-family home in Lynn runs in the $70,000s and $80,000s. Two- and three-family houses are hitting the $80,000s and $90,000s, says Mazie Meedzan of A. James Lynch Inc. in Lynn.

Prices in Lynn have shot up, and it may be partly due to city revitalization plans, say Realtors. The downtown area was ravaged by a fire in November 1981, but now ''Lynn is really on the rebound,'' says Realtor Christine Todd. The North Shore Community College will be moving into a new building downtown, and the foundation has just been poured for ''Seaport Landing.'' This $20 million project includes a four-acre waterfront park, 105 luxury condominiums priced at

Next door in Revere, there may be more condo developers pacing the shoreline than sunbathers. ''A lot of money is being pumped into the Revere Beach Parkway, which has been terribly undeveloped and neglected for years,'' says Mrs. Todd.

Developers have already unloaded a wad of money along the docks near downtown Salem. Adjacent to a grassy Salem Maritime Park are $130,000 condos and Quincy Market-type eateries and boutiques perched on Pickering Wharf. While there is little room for further waterfront development, lately the rambling mansions built by 19th-century China-trading captains are being subdivided into condos. The same thing is happening in Newburyport and Marblehead, says Mr. Carlson of Carlson Real Estate.

Density of the North Shore population, lack of land to build on, and soaring prices have fueled the condo trend. ''Anytime the values of properties don't allow young people to move in or prevent older people from (selling their large homes and) staying, you will see condominiums,'' Carlson says.

From condos to multifamily dwellings, the market has been ''unbelievable. Demand far exceeds the supply of homes,'' says Dorothy M. Shea, executive director of the Eastern Middlesex Board of Realtors.

After two years of sitting on the sidelines, buyers burst onto the market in record numbers when interest rates came down last year. Now, would-be homeowners are making a last dash to buy as rates push the 14 and 15 percent level.

''For the past six months the market has been crazy. We can't keep a house priced in the $70s,'' says Marge Carey at James Lynch Realty, Peabody. ''If you're selling a two- or three-family home, just about any price you put on it, you'll get.'' Throughout the Greater Boston area, Realtors report hikes of 10 to 20 percent over last year.

But Carlson sees a shakeout ahead. ''There are too many people in the business. (A month ago) there were 360 residential listings and 900 brokers. That's 4/10s of a listing per person.'' Unless interest rates climb above 16 percent, buyers will abound and the supply of homes will remain low. And prices , he says, will continue to rise.