Previews Inc., an international real estate marketing firm, concerns itself with properties that most of us only dream of owning.

But it's fun to leaf through Previews' annual Dream House Catalog -- a marketing device that has its own Library of Congress catalogue number.

This year you can fantacize about Previews' offering of a small Japanese castle, disassembled in 1978, but available for $1.5 million to be erected on any site you chose -- any where in the world. A team of Japanese carpenters will travel with the house to its new site and rebuild it there.

You could also go for Previews' romantic bridge house near New Canaan, Conn. Built over the Ripowam River, this house has vaulted, gold-leaf ceilings connecting four wings at each corner of the central span. There's a guest apartment and a three-bedroom children's wing on the three-acre site. Furnishings are available under separate negotiation.

Interested in something closer to home but a little more expensive? It's the Winter Place Farm near Salisbury, Md. Maybe you've seen it on your way to Ocean City. This 222-acre horse ranch has been on the market for a number of years. It's listed at $3.9 million.

For dreamers with smaller incomes, the Dream House Catalog includes an $85,000 country home furnished in antiques. Located near Superior, Wis., the five-room rambler looks like one that tract developer William Levitt might have built on Long Island 30 years ago -- on a smaller lot. This five-room house is on four acres, with a brook and fruit trees.

Published by Harmony Books in New York City, Previews' new Dream House Catalog (192 pages) is sold in bookstores for $10.95. CAPTION: Picture, This old Japanese palace, disassembled in 1978, is on sale for $1.5 million. Previews, Inc.