I would give my vote for the Yate Loon 80mm Low Speed fan. I bought two of them a little while ago. One for use on my new HR-05 IFX chipset sink, and one as a side fan on my case. It says 25CFM @ 26dB.
I don't go much by dB ratings as they don't tell you anything about the distance they took the reading *cough* thermaltake *cough*. I just read reviews and personal experience. All I know is I can hardly hear it when I just sit it there and I can't hear it at all in my case (Though lets face it I got two 120mm 90CFM fans in there too

)
Still that's what I would recommend. Cheap and very affective.
80mm Yate
BTW, is anyone else noticing that the Jabby site is running slow as molasses this morning? Took me 5 minutes just to get a link..