The 4" manual plastic rain gauge is available from the following retailers.  
Prices may vary.  Click here to read more about approved gauges for CoCoRaHS.

WeatherYourWay.com (the official CoCoRaHS gauge supplier)

Climalytic Instruments (manufacturer of the premium CoCoRaHS TROPO gauge)

Forestry Suppliers

Weather Shack.com

Scientific Sales

Ambient Weather