Unless Dunlop has totally changed the DC brick, it is just a 1spot/Powerall with different casing, ie it is not isolated or anything, so 100 quid is too much for it.
The best solution is in Netherlands , the Burkey Flatliner at around 200eu, but unfortunately the dealer network is TINY, just 3 shops in the Netherlands, i just wish someone brought it in the UK.
As for 1spot/Godlyke, it seems like the same thing, with the exception that the Godlyke ends up beeing cheaper at 40quid including every posible lead/adapter.