Resources For Learning Southwestern Mandarin (西南官话)
Michaelyus's answer to a similar question (link in the comments above) is still very useful.  

A general resource that unfortunately may be hard to find now is the 現代方言音庫, a series published by the 上海教育出版社 in the mid 1990s.  This series consisted of a thin booklet titled XX音檔 (usu 100-150 pages) and a good quality cassette for each dialect. The series eventually covered 40 plus dialects, including 成都，貴陽，and 昆明, and the booklets were often written by well-known experts; for example, 成都話音檔 was written by the late 崔榮昌，who did much important work on 四川 dialects. In addition to characters, pronunciation is given in IPA, which I found very helpful.

One problem there may be in making a list of resources for 西南官話 is that it includes a large range of sometimes pretty different dialects.  For example, the varieties spoken in Hubei are sharply different to my ears from 成都 and 昆明.