It's hard to say any multiplier how much brighter the screen is than before as I didn't get any comparsion pictures for it because of some issues:
This chinese miracle screen takes the +12V via VGA cable from pins that should according to some standards be +5V. Foolishly I plugged this screen to my desktop PC with regular "all pins connected" VGA cable and the result was a broken HD4870 card and broken DVI input of my 24" monitor. At the time I didn't have suitable VGA cable to run this screen with PC as the original cable is attached to my car, so I never got change to feed test image to this monitor and couldn't take comparsion screens unfortunately.
It's also been really ****ty and cloudy weather in finland lately so no real sun light tests for now. But as the screen was quite readable in sunlight with original backlight, this can't be any worse. When comparing this screen next to my 24" samsung 2493HM, it's quite as bright and the samsung is REALLY bright. I'd bet this beats most of the CCFL screens they sell for cars (in brightness).
I have Canon Ixus860, Ixus40 and S5 IS cameras so if someone wants I can take a picture of the screen in full brightness with some specific exposure/aparture settings and if someone has one of those cameras, you can take a comparsion picture with same settings.
Leds cost me 35 euros (102 of them), 2 PCBs and resistors 25 euros, but I got some discount from this nice guy from electroforge who also helped me along the project.
You can order the leds from any big led store and I'll bet you can get them cheaper. Cost of custom PCBs varies a lot and you should compare the prices and what they include. Few stores that you could check (took the list from a finnish forum):
AtTiny15L micro controller cost less than 4euros, FET for power supply less than 1 euro, so the PWM really doesn't do much for total price.
Of course if you don't want multistep dimming it isn't any good for you and you get no benefits of using it.
BTW. in those led banks the leds are generally quite far apart each other so the light source won't be that uniform and you might not get that even lighting atleast in the edges. Something that you need to keep in mind.
Simplex, I don't have "hot air soldering iron" (don't know what's it called in english) so the result with these tiny smd components isn't that professional and it isn't that fun either So I'd politely refuse from this honor. Of course you can ask from the electroforge guy an offer how much would it cost if he makes the PCBs and puts it all together for you.
As for the micro controller, I'll atleast share the code here when it's done and maybe I could send a pre-programmed chip for you. Tho I cant give any promises when that would be as I'm quite busy at the work and also have stuff to do at home + I still have to finish the code so it works without glitches.