Beatrix Potter was going for $1.69, Dorothy Rodgers for under a dollar. Such were the remainder books during the opening weeks of Crown Books in Rockville. Paperbacks could be found at two for $1, gold-tooled blank books to write yourself, under $2. But, appealing as those buys are when you are browsing through a bookstore, the big draw at Crown Books is the discount on best sellers: all books on the New York Times hardback best seller list are thirty-five per cent off, paperback best sellers twenty-five per cent off. All other books are at least twenty per cent off, and even magazines are discounted about ten per cent. The choice is wide, with two long walls of paperbacks in categories from astrology to westerns, and the center aisles stacked with art books, children's book, even calendars. The store issues rain checks on best sellers not in stock. And, being open seven days a week, most days until midnight, Crown is ready for you when you're seen the movie, and have a sudden urge to read the book.

Crown Books, 12111 Rockville Pike, Rockville. Open Monday through Saturday, 9:30 a.m. to midnight; Sunday, 9:30 a.m. to 9 p.m. 881-6113 .