See if you can get your hands on a copy of "The Writer's Guide to Everyday Life in the 1800's". These guides are part of a series of books geared toward writers who need to know about the trappings of daily life within a specific time frame.
Old bound issues of magazines from the period would also be helpful although unless you live in or near a major city may be difficult to find. It might be helpful to look through back issues of newspapers on microfilm (The New York Times, for example, can be accessed at many college and university libraries on microfilm) and look for ads that included drawings of styles.
Sears and Roebuck catalog reprints are available but they won't be of any help to you because Sears specialized in watches and jewelry in their early years which began in 1886. Clothing wasn't added to the catalogs until the late 1890's.
Look for movies with a setting in the mid-1880's or look for biographies complete with many photographs of that era.
Online sites that might help include
www.fashionera.com. You might also type various word combinations into your favorite search engine and go from there.
Good luck!