I have with succes used these:

http://www.aliexpress.com/item/Travel-Convenient-EU-Plug-Wall-USB-Charger-Adapter-For-Samsung-Galaxy-S5-S4-S3-Note-3/32220133044.html

They are really easy to dismatle, and the result is this - https://www.dropbox.com/s/ep43uyve5v0msv6/20141206_214210.jpg?dl=0

At $1.10 I didn't even think about making my own PSU :)

Ok, finally got it to work with this:

// Example sketch showing how to control physical relays. 
// This example will remember relay state even after power failure.

#include <MySensor.h>
#include <SPI.h>
#include <DallasTemperature.h>
#include <OneWire.h>

#define ONE_WIRE_BUS 3 // Pin where dallase sensor is connected 
#define MAX_ATTACHED_DS18B20 16
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);
float lastTemperature[MAX_ATTACHED_DS18B20];
int numSensors=0;
//boolean receivedConfig = false;
boolean metric = true;
#define RELAY_1 5  // Arduino Digital I/O pin number for first relay (second on pin+1 etc)
#define RELAY_2 6
#define RELAY_ON 1  // GPIO value to write to turn on attached relay
#define RELAY_OFF 0 // GPIO value to write to turn off attached relay

// Motion sensor defs
unsigned long SLEEP_TIME = 10000; // Sleep time between reports (in milliseconds)
#define DIGITAL_INPUT_SENSOR 4   // The digital input you attached your motion sensor.  (Only 2 and 3 generates interrupt!)
//#define INTERRUPT DIGITAL_INPUT_SENSOR-2 // Usually the interrupt = pin -2 (on uno/nano anyway)
#define CHILD_ID 3   // Id of the sensor child

boolean lastTrippedState;

MySensor gw;
//
MyMessage msgTemp(0, V_TEMP);
MyMessage msgRelay2(2, V_LIGHT);
MyMessage msgMotion(3, V_TRIPPED);

void setup()  
{   
  gw.begin(incomingMessage, AUTO, true);
  gw.sendSketchInfo("Temp/Relay/Motion Sensor", "1.0");
  //
  gw.present(1, S_LIGHT);
  pinMode(RELAY_1, OUTPUT);
  //
  gw.present(2, S_LIGHT);
  pinMode(RELAY_2, OUTPUT);
  digitalWrite(RELAY_1, gw.loadState(1)? RELAY_ON : RELAY_OFF);
  digitalWrite(RELAY_2, gw.loadState(1)? RELAY_ON : RELAY_OFF);
  pinMode(DIGITAL_INPUT_SENSOR, INPUT);      // sets the motion sensor digital pin as input
  //
  gw.present(CHILD_ID, S_MOTION);
  
  // Fetch the number of attached temperature sensors  
  //numSensors = sensors.getDeviceCount();

  // Present all sensors to controller
  //for (int i=0; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {   
     gw.present(0, S_TEMP);
  //}
}
//
void loop() 
{
  gw.process();
  boolean tripped = digitalRead(DIGITAL_INPUT_SENSOR) == HIGH;
  if (tripped != lastTrippedState)
  {  
    Serial.println(tripped? "tripped" : "not tripped");
    gw.send(msgMotion.set(tripped?"1":"0"));  // Send tripped value to gw//
    //digitalWrite(RELAY_1, tripped? 1 : 0);
  }
  lastTrippedState = tripped;
  
  // Fetch temperatures from Dallas sensors
  sensors.requestTemperatures(); 

  // Read temperatures and send them to controller 
  //for (int i=0; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {

    // Fetch and round temperature to one decimal
    float temperature = static_cast<float>(static_cast<int>((gw.getConfig().isMetric?sensors.getTempCByIndex(0):sensors.getTempFByIndex(0)) * 10.)) / 10.;

    // Only send data if temperature has changed more then 1 degC and no error
    if (int(lastTemperature[0]) != int(temperature) && temperature != -127.00) { //added integer

      // Send in the new temperature
      gw.send(msgTemp.setSensor(0).set(temperature,1));
      lastTemperature[0]=temperature;
    }
   //}
}

void incomingMessage(const MyMessage &message) {
  // 
  if (message.type==V_LIGHT && message.sensor == 2) 
  {
    // Change relay state
    digitalWrite(RELAY_2, message.getBool()?RELAY_ON:RELAY_OFF);
    // Store state in eeprom
    gw.saveState(message.sensor, message.getBool());
    // Write some debug info
    Serial.print("Incoming change for sensor:");
    Serial.print(message.sensor);
    Serial.print(", New status: ");
    Serial.println(message.getBool());
  }
}