It might be hard to acquire at an affordable rate, but the Cambridge History of China, Vol. 5, Part 2 will be a great resource for Song economic history. And I haven't read it, but William Guanglin Liu's book on Song economic history (also covering the following eras) is likely a worthwhile read on this topic.

Stephen Owen's All Mine is thoroughly researched and a very enjoyable read. It's not exclusively economic history, but it explores the era's commercial revolution and its impact on philosophy and literature. On a similar note, Jing Xie's Chinese Urbanism: Urban Form and Life in the Tang-Song Dynasties discusses the interplay between economic evolution and new approaches to urban life.

This is an academic article (free with a JSTOR account), but Liu's exploration of Song financial policy is a worthwhile read that dovetails with broader economics. It follows the establishment of a revenue system based on non-agricultural taxes (corresponding with the increasingly commercial economy).