Quantity   Component name
1 × Cheap efficient replacement laptop power supply (12 Eur) http://www.leicke.eu/de/products/NT03012
20 × Sebson Media GU4 LED module (90 Eur) http://www.sebson.de/g4-led/led-g4lt-smd12/a-110/
1 × Steel cable, 20 meters (8 Eur) local hardware store - take a multimeter with you and measure resistance, ignore the confused looking other customers ;)
4 × ?-Hooks (3Eur) local hardware store
40 × Crocodile clips, just buy the cheapest "lab cables" from ebay (4 Eur) ebay
8 × wire rope clips (3 Eur) local hardware store
2 × turn buckle (3 Eur) local hardware store
1 × Sum: ~120Eur