I came across the following paper which gives interesting data on expenditures of poor people in developing regions.

The economic lives of the poor.  A. Banerjee and E. Duflo,  MIT Working paper,  October 2006.

http://www.cs.washington.edu/education/courses/csep590b/CurrentQtr/docs_p/banerjee_duflo.pdf

It is worth reading.  (For csep590b,  I’ve put it as a supplementary reading for week 6. http://www.cs.washington.edu/education/courses/csep590b/CurrentQtr/readings.html)

- Richard