My last few PCs have been as silent as possible water cooled builds. Zalman heatpipe PSU, no HDDs WC CPU, GPU, Mobo etc etc... I've tried dozens of different fans but have found Noctuas and 1150 Gentle Typhoons to have the best CFM/DBA ratio. If you are looking for cheaper fans; Antec TrueQuiets or the Nexus/Yate Loon 1000rpm fans are your best bet, but not as good as the noctuas/GTs.
If the colours are a real turnoff, the noctua's can be easily painted and while I expect that they lose some of their efficiency, it's not enough for me to notice by comparing a stock to a painted fan. Here is an S12b that I use as an intake on my secondary PC. Gloss black frame with UV active green rotor.