I spend about £6 on mine, £3 for the adapter and £3 for the 12" cathode from ebuyer. I'm waiting till night time to take a pic of mine and add to this
Here's my other tank:
If you have problems with the picture turning out too dark, try adjusting the iso speed if your camera allows. Put it at 100+, that's how i got mine to turn out light. Without it mine also turned out dark