Has anyone looked at using some of these things for regulating the car's ~12v to clean power? I've been looking all over for some cheap and simple solutions for powering my LCD and Reverse Camera at the same time. Yes, I will have a PC with a M2-ATX PSU, but I don't necessarily plan to have the PC running all the time.

Anyways, here's what I've stumbled across, please give your feedback on why nobody (or few) are using these to regulate 12v.

1a) Solar Panel regulator

This is supposed to regulate input from a solar panel to charge a 12v battery and/or provide an output of 12v... at least that's what I get from it. And for only about $20!

1b) Another one

Much more expensive...

2) Old Car regulator

This looks kinda scary, but maybe it's useful? About $20 shipped from eBay, but I bet you could find 'em cheaper from a wrecker or junkyard... Or I could be missing the whole point of what it does.

3) Universal Car Adapter (cigarette lighter plug)

This looks perfect, and on clearance for $20! But I'm wondering what the mA output would be on it... ultimately I will need 300mA for the reverse cam (with IR on, so at night) plus 800mA for my TM-868 LCD. Is it likely this thing will provide ~1A+? Maybe I'll go to the store tomorrow and see if it says on the packaging anymore info.

4) Universal Laptop adapter *modified*

I've actually got one of these I'm not using, so I was thinking since the output range on them is 15v to 24v, why not leave it at 15v and use a 7812 (or whatever) to regulate it back down to 12v? I know this would be inefficient (not as bad as battery (DC) > inverter (AC) > PSU (DC) ) but then maybe the unit could be modified to allow a 12v option? I've never opened it, maybe that's something to look at. Cheap at about $13 shipped.

5) My own idea... for the reverse cam anyways:
Ok, so I'd like to be able to have the reverse camera turn on with the reverse lights, and on my car the lights only work when it's running so the voltage is around 14v. Also, I want to be able to manually turn on the camera, when the vehicle is off. So what if I use a 3 position (ON-OFF-AUTO) switch, and the line from the Reverse lights (~14v) would be regulated with a 7812, and then the manual ON would be wired directly to the battery (since the car is off, this should be very close to 12v), would that make sense? It doesn't solve anything for the LCD (maybe I'd use #3 for that) and I'd have to remember NOT to use the manual setting when the vehicle is running, or I'd shorten (or fry) the camera.

6) Suck it up and use the 12v rails from the M2-ATX:
By my calculations, I will be getting very close to overloading the 12v rails if I try to run the LCD and camera off it, in addition to the PC.

So please give me your comments and thoughts on what I should do for this, I look forward to your replies!

PS: I did quite a bit of searching on the forums, but I apologize if I missed a thread or post that covers everything exactly...