Good
The current costs to build a cistern  is about $950 U.S. (no pump).  This is for a cistern that will hold between 10,000 -  16,000 gallons of water.  This includes a system to catch rain water and funnel it into the cistern. Add a few hundred dollars for a hand pump.

Better
To dig a well costs about 10 U.S. per foot. Therefore a 100 foot well would cost a minimum of $1000 U.S.  To add a hand pump would be another $200-600.  To add an electric pump will cost about $600-800 U.S. plus the cost of gas or electricity, another $400 a year.  A working estimate for a 100 foot well with electric pump $1,600 -2,000 U.S. with a $400 / year operating budget.    Most wells will need to be between 100-140 ft deep, though some go as deep as 300 ft.  Additional hand pumps.

Best
To dig a well that is completely sustainable without  the need for international maintenance and without the yearly diesel / electric expenses (better in the long run) will be about $5,000 - 11,000 U.S. depending on the depth of the well, the size of the system and the pump.  This is a system that would run off either a windmill and / or solar.  The cost is higher but averages out to a maximum of  $22.00 a person for a lifetime of clean drinking water.  For the Bergey system below the cost per person for a lifetime of clean water is $14.00 U.S. 

To put this in perspective you can buy three 12-packs of bottled water for the same cost of providing a Haitian with clean water for a lifetime.

Aquafina Water 12 Pack of 1/2 Liter Bottles 192.00 fl oz

$0.04 $7.291 Price/fl oz Price

1 kW XL.1 Turbine, with PowerCenter     64 ft. Tilt-up Tower      5.3 kWh Battery Bank (B220-4) 1,500 W Inverter System (DR1524, with fuse) 120/240 VAC Transformer Grundfos 22 SQ-120 Submersible Pump                         Total Cost:

$2,590 $1,595 $450 $1,044 $250 $1,132 $7,061

¹  This information is from www.Netgrocer.com, April 28, 2007.