All the components except for batteries and charger will cost about 43 € not including shipping and the time finding the parts.  If you  need parts write me.  

Total self purchased cost not including shipping including batteries (Aldi or Lidl)  and multi- charger is 67€.   The individual costs are below.

Tubelight Materials

1x  50mm HT Tube +  1x 50 mm HT Cap  1.50 € (Hornbach, Praktiker, Hella)

1 x MR 16 - 5 W 12V LED  18.95 € + shipping (LED's and more .de)   Ebay seller

1 x Cateye handlebar clamp H32 (22-26 mm bars).   H31 for 28-32 mm.  $2.75 - 4.95€ + shipping

1 x Cateye Handlebar Spacer Model: 533-8730 for Handlebar clamp H32 or H32. $2.00 + shipping

(Quick disconnect plate)

1 x custom molded epoxy-glass fiber adapter for 52 mm Ø to flat to Cateye Spacer 533-8730.    order from me 2 €

Click here for adapter dimensions.

2 x  5 mm diameter x 5.5 - 7 mm long set screw + 2 steel pins 1.8 mm diameter 5-8 mm long. 0,05€

1x M4 x 12 mm or M4 x 14 mm Panhead screw. 0.06 €

1 x Halogen Lamp GU 5.3 socket with leads:  Conrad 558311- 62  3.30 €

2 x Female 5 mm x 2.1 mm connector:  Conrad 733948-62 0.91 € (one for the Tubelight, one for the charger adapter)

1 x Toggle switch with screw connections Conrad 700000-63  2.35 € (need to cut square opening in the end cap 12 mm x 19 mm)

3 x 10mm 3/32" long shrink tubing. (5 pieces if you make a adapter for the charger)  10x200mm 2.62€

1 x multi-charger.  Conrad 232622-32 14.95 €

One of the following power cables. 

1 x 1 meter cable with 5.5x 2.1 mm straight connector Conrad 710344-62  1.07 €

1 x 2 mm cable with 5.5x2.1 90 Degree connector Conrad 734197 - 62 1.46 €

1 x 9V battery clip Conrad 490660-62 0.29 €

1 x battery holder for 10 rechargeable AA batteries  Conrad 615617-62  2.25 €

AA Ni Mh rechargeable batteries seasonally on sale at Lidl or Aldi 2.99 € for 4x AA batteries (2300- 2500 mah)   Total cost for 12 batteries: 9.00 €

Water bottle 3.00 €.