I have used a fan from an old amd cpu, connected it by using one of my unneeded usb cables, fan is spinning, but it's obvious it doesn't ran at full speed.
This is a 12V fan, so the speed is much lower than it should be, 5V of course, isn't enough to achieve max rpm's.
Second step is needed for the fan to have a purpose, i need to modify the upper side of the case, or maybe make a new upper part, so the fan can fit and cool the device.
This shouldn't be tough, but it probably won't look as beautiful as original case, but i could live with that.
Did a few seconds testing holding it with my hand, temperature fell to 37°C, lower than 43-44°C without the fan, tested without any Linux app running.
This doesn't mean i won't buy a fan, i will buy it as soon as it comes out, but if it will help me before you start selling case and fan, then why not.