Tim,
I got my 24V 40 mm x 10 mm fans at 3DMakerWorld (
http://www.3dmakerworld.com/store/parts ... ll-bearing). The specific fans are labelled:
Fonsoning
DE brushless fan
Model FSY40B24M
DC 24V 0.06A
and they have the CE mark and TUV Product Service mark. They are 9-blade ball-bearing fans and seem to be not ridiculously loud.
And, yes, I've wired two 12V LED strips in series, then paralleled that assembly with BOTH the 24V 40mm fans. (I upgraded my M2 from 19V / 12V to 24V but DID NOT replace the wiring harness. So my two 40mm (24V) fans are in parallel. I also tweaked the firmware to run them at 255/255 -- full on -- not 155/255 as was done with the 19V power and 12V fans on the original M2. I've also set my firmware for 400 Hz PWM of the fans instead of 31 kHz PWM -- all my fans are now VERY well behaved for speed control.)
The LED strips are from Radio Shack. I bought two spools of white LEDs (for something else), and I used the little pre-terminated and heat-shrink-over-the-connections 3-LED strips that are part of THE PACKAGING! TRY ME NOW!!!

(Plus I have a couple little batteries and a couple little pushbutton SPST/NO switches from the packaging as well! RS sells the switches for a couple bucks for two, so that saved another purchase right there!)
So I had to add the comment and the info in the instructions to my Thingiverse posting about my unique printer wiring.
I suspect with the newer M2s with 24 volts, you could probably find the wires in the harness that go to the extruder 40mm fan and re-do it so as to use 24volt fans in parallel. I'll have to get out the harness that came with my 24V upgrade kit and see.....
Hope that answers your questions, Tim.
I've added a few other strips of LEDs with a little RF-remote controller that makes my M2 a real take-to-shows-and-STEM-events wowser! See
viewtopic.php?f=3&t=132&p=981. (And of course, while I was searching for that, I found the other posting I did on this bracket in the "object sharing" forum. D'ohh!
viewtopic.php?f=4&t=330&p=2035. Sorry for the duplication!)
Dale