For some reason I thought it was a booster, I guess not..
Here it is:
http://www.ebay.com/itm/1pcs-DC-DC-Buck-Converter-Step-Down-Module-LM2596-Power-Supply-Output-1-23V-30V-/370772814758
I use it to power my custom ATMega644P board that also has RTC, WaveShield and 32x16 LED matrix display...