Please see our Affordable Housing Forum [1] for the cheapest housing listed in the San Diego region. If you can't find what you need, try the links listed below.
Craigslist.org [2]
San Diego Housing Commission's Affordable Housing Locator [5]
San Diego State Off-Campus Housing [6]
Links:
[1] http://www.ucan.org/forums/affordable_housing
[2] http://sandiego.craigslist.org/hhh/
[3] http://sandiego.houserebate.com/
[4] http://www.chworks.org/affordable_housing/default.asp
[5] http://www.sdhc.org/giaffordhousingnews1.shtml
[6] http://www.sdsu.och101.com/
[7] http://www.ucan.org/taxonomy/term/18