I bought a new akasa apche to test it's sound level. I tested it for about 5 minutes... not silent, louder than the Noctua NF-P12 (though more cfm and pressure too).

Louder than my existing fan = my decision to sell the apache.

Sidewinder is the only source in the US, and they sell it for exactly $18.82 including their cheapest shipping option.
I'll offer this 5-minutes-from-new one for $12 including priority shipping.
The fan, box, and rubber-fan mounts are all like new.

If you have a high ranking or references, I can ship the fan and you can pay after receiving it.
Otherwise, I'll ship the fan after $6, and you can pay the rest after receiving it. - paypal only
I can also post it to ebay (already listed actually).

How can you compare the two.

The AKASA is a PWM fan with a relatively low (for a PWM fan) top speed of 1500. The Noctua operates at something like 800 to 1200 rpm spending on what speed you set it to run. I think maybe the only competition for the Akasa are the PWM slipstreams. The slipstreams appear to be able to run slower... though I suspect they are not so good when faced with high static pressure... where maybe the Akasa might be good.

Would you mind telling us a bit more detail on what speed each was running and on what circumstances?

When plugged into an external AC->DC 2A adapter, at 12v, sitting on an open table, the Akasa was louder than the NF-P12.

Not saying it was 'loud', simply louder than my current fan. (I was looking for quieter). To what degree? ... maybe if the akasa was about 3 feet away, and the noctua was next to me, that may have resulted in a similar sound level.

They also had different sound signatures.. from what I remember the noctua was more low-pitched. But both were rather gentle sounds, mostly from the airflow itself. The ears play tricks on perception when trying to analyze 2 fans that are close in sound.
But the Akasa definitely had more sound, at 12v, in the open, than the Noctua.. is why I am reselling the fan.

The Akasa also made clicking occasionally when under-volted with an external fan controller (Sunbeam RheoSmart 3). Apparently some fans work silently with specific external controller technology and others don't. I've only used a fan controller on 3 brands of fans, the Apache, the NF-P12, and 120x38mm SilenX's. Out of the 3, the Noctua didn't click (the SilenX fans clicked when using a SilenX external fan controller... I'm unsure if that was also a rheobus technology or another type).

As for cfm, with the basic feel from a hand, the Akasa felt to push more air without a doubt.

no bites.. so reduced to $12 including the priority shipping.

Seems like in typical use you would probably be running the Noctua using one of its speed reducing cables... so it would even quieter... running at around 800 rpm instead 1200. and you would be running the Akasa using 12 volts with PWM controlled speed at far less than the 1500 rpms you tested it at.

Try running the Akasa on PWM and compare it to the Noctua running with one of the speed slowing cables. It might change your assessment of the two fans.

I don't use PWM (I use a laptop). The fans are for external cooling and air filtering.
So, for my purposes, I need a fan that can be undervolted using a external fan controller.

I did figure that the akasa clicked because of the external fan controller, and that it would not click when used as it's designed to.. with PWM.

... make that $11, including Priority shipping.

getting it new costs $18.82.