Although the power supply says 9 volts the lowest this one could go reliably is 5 volts I would say four double AA batteries
Photoresistor (around 5kΩ in light, 200kΩ or more in dark)
Transistor NPN BC547,PNP BC557
Variable Resistor (potentiometer)100 kΩ
Resistor 390 Ω
Light-Emitting Diode LED