For quiet 120mm fan recommendations head over to www.silentpcreview.com - they know what they're talking about.

http://forums.silentpcreview.com/viewtopic.php?t=16393

In the UK, the papst 4412 is available at coolercases for 13 pounds.

I personally wouldnt recommend the 120 titan for our application, as at 7v it pushes an extremely average mount of air, and it still quite audible. At 5v, they're not bad fans though - so if you're after a quiet pc fan, they're cheap that way.
My local electronics chain, Dick Smiths Electronics (AUS + NZ store like ratshack), has a titan plastic 120mm fan for 12NZD (7USD, probably around 4 pounds), which is basically identical to the titan 120mm alu fan. Some of you will recognise the 120mm alu fan as being an evercool - evercool rebrand the titan fans + fabricate a noiselevel 5db lower, and sell them for 2x the price.

In the US, look at the threads in the SPCR thread - its not hard to find stuff in the US (lucky fellas).

If anyone finds fans from the SPCR thread in their local area, feel free to add them...

Whats even more interesting, is the 38mm 120mm AC fan recommendations, so if anyone finds those locally, please put up your links

interesting suggestions... now have a look at these.

http://www.3dcool.com/index.php?cPath=445_447

i have used the 120mm/14dB silenx fans and they are impressively quiet. they come with these silicon screws/nail dealiebobs that may or may not require a reboot of your fan mounting. they do a very good job of cancelling out vibration.

one caveat: they do not stand up to excessive heat, i.e. the heat from 575w hmi lamps, and the frame warps to cause a buzzing sound, almost like a film projector. i think the ushio and other mogul 400w lamps are not as much a problem. they are definitely worth checking out. if your cooling design is as focused as mine, or is your rig warps the silenx fan, return it and try the aluminum fans sold at 3dcool. the aluminum does a wonderful job disipating the heat, at the cost of a few dB.