I've just made another DIY controller - a spare - for under £15. These are class, they only require calibration once (the air temperature doesn't affect them), and they don't require a battery in good nick to work either; they'll run on any old 12v battery.
I've included an on/off LED switch - though I think that's superfluous to requirments; it would work without it and be even simpler to produce. An LED on/off switch lets me know if it's on at a glance, and it also means I don't have to turn the dial to turn it on (I'm very lazy).
Anyway, these are the parts I purchased:
12v LED rocker switch £2.00
http://www.ebay.co.uk/itm/261513977084?_trksid=p2060778.m2749.l2649&var=560391577650&ssPageName=STRK%3AMEBIDX%3AITWaterproof Project Box 115*90*55mm £4.52
http://www.ebay.co.uk/itm/201212241692?_trksid=p2060778.m2749.l2649&var=500405437151&ssPageName=STRK%3AMEBIDX%3AIT10A 12V~40V PWM DC Motor Speed Control Switch Controller Volt Regulator £7.00
http://www.ebay.co.uk/itm/10A-12V-40V-PWM-DC-Motor-Speed-Control-Switch-Controller-Volt-Regulator-Dimmer-/121250426718?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item1c3b16af5eI drilled the holes for the voltage regulator and the switch and a hole at the rear for the wires that go to the pump and the battery:
Then I wired it up; soldering the wires on the switch (first time soldering; which why it looks rough):
I was unsure how to solder or wire a rocker switch, but it's all on youtube:
How to wire a rocker switch:
https://www.youtube.com/watch?v=cQpQWFYX524How to solder:
https://www.youtube.com/watch?v=BLfXXRfRIzYThe wiring on the voltage regulator is easy; on the rear it tells you what's what, with regards motor +- and battery +-.
I quite enjoyed doing it too.
If anyone fancies a bash, don't be shy to ask questions, though it's pretty straightforward.
And if anyone can suggest any improvements, I'm all ears.
Oh, Ionics sell a similar, with VAT and delivery, it's £210.00
And it doesn't even have an LED switch on it!