I just picked up some of these cougar fans
and am very pleased with them. They were on sale over thanksgiving for 10 so I'd expect them to be on sale again for X-mas. I run 2 intakes and 1 exhaust.
The noctua fans I have are also very quiet but i prefer the sound signature of the cougars. I did have an issue with running a mixture. My cpu fans are noctua and the exhaust fan is less than 2 inches from the pull fan. I was getting a strange whine/whirl sound. A little tweaking with easy tune took care of it.
How much airflow do you need?
You should also spend some time reading the SPCR guide