This is the parts list for SMS controlled Hot Water Heater
Detailed at www.forward.com.au/pfod/pfodSMS/SMS_HotWater.html
(approximate prices as at 6th Jan 2015, shipping extra)

Arduino Mega 2560 -- https://www.sparkfun.com/products/11061 (~US$50) or SainSmart MEGA2560 R3 (~US$30)

SIM900 based GPRS shield --
 http://www.seeedstudio.com/depot/gprs-shield-v20-p-1379.html GPRS Shield V2.0 SKU: SLD01098P (~US60) -- I used this one.
 OR 
 http://imall.iteadstudio.com/im120417009.html ICOMSAT Model: IM120417009 (~US42) -- this one should work also if you select it in pfodDesigner but not tested yet

Screw Terminal Shield -- ITEAD PROTO SCREW SHIELD Model: IM120417013 http://imall.iteadstudio.com/im120417013.html (~US$4)

USB power supply 1A -- https://www.sparkfun.com/products/11456 (~US$4)

Solid State Relay -- FOTEK SSR-40 DA amazon (~US$14) also from numerous other sources look for one with a cover

Solid State Realy heat sink - Aluminum Heat Sink for Solid State Relay SSR Small Type Heat Dissipation, amazon (~US6) also from numerous other sources.

Heat Sink Compound -- https://www.sparkfun.com/products/9599 (~US$2)

pfodDesigner -- https://play.google.com/store/apps/details?id=au.com.forward.pfodDesigner (free)

pfodApp -- https://play.google.com/store/apps/details?id=au.com.forward.pfodApp (~US$8)