Sears, Roebuck & Co., the largest nonfood retailer in the metropolitan area and across the nation, has begun to install new women's apparel budget shops at its larger stores in Washington, Baltimore and Annapolis.

According to William I. Bass, area general manager for Sears, the budget shops will include sportswear, dresses, suits, outerwear, intimate apparel, hosiery and accessories.

The decision by Sears to expand the concept of budget stores here comes at a time when affluent-oriented retailers such as Bloomingdale's have opened initial stores and Woodward & Lothrop, the local department store firm, is dropping its budget stores.

Sears is adding the budget stores nationwide and expects 400 stores to have the separate shops by year's end.

"The whole point . . . is that fashion doesn't have to cost a whole lot . . . what we're offering is the choice," Bass said.

He said that among lines to be carried in the shops will be "zip and dash" dresses in washable prints and solids at $8.99 and $10.40; pants proportioned to fit every type figure at $6.99; and interchangeable separates starting at $3.99.

The new departments also will carry a line of professional uniforms as well as hosiery and lingerie designed for wear with such outfits. Sears operates 16 retail stores and six other sales and service outlets in the D.C. area, with sales estimated at $250-$300 million a year.