This is a pretty good, and very recent, thread about sorority financials:
http://www.greekchat.com/gcforums/sh...ight=financial
It explains some of the nuances and differences in sorority dues. Remember that many chapters that look cheaper on paper are omitting payments for favors, some formals or photos. Chapters that look more expensive often include a small fund for favors, and cover the costs of most/all activities. Don't try to base your rankings during recruitment on costs - it'd probably be futile, anyway.