Many costumes can be created by adapting clothing found in thrift shops and used-clothing stores. Women Petticoats can be made by cutting off the skirts of 1950s evening gowns or any long, full-skirted dresses. White, long-sleeved blouses that button up the front or back are great. Look for knitted or crocheted shawls. Lace doilies make great day caps just add ribbon and some silk flowers.
Men Find baggy pants and taper the legs down or remove the cuffs.
Buy an old vest and square off the bottom by folding under the points. Adapt white shirts by cutting off the fold-over collar right at the top and finishing off the edge. A sack coat can be made by shortening an old overcoat to fingertip length.