I did a smaller, simpler build with 8 x hotswap-bay SATA drives running off two 4-port PCIe SATA controllers.
Not counting drives, it came to about $550.
I originally started building it around a Dell YK838 SAS 6i PCIe controller card, but got tired of fiddling with using other systems to reflash the firmware and then having to mask off pins on the PCIe connector to get the system to even POST.
I replaced all the "factory" fans, as well as the two on the back of the hotswap drive modules, with Noctua equivalents.
http://www.mrbill.net/nasbuild/
I originally started building it around a Dell YK838 SAS 6i PCIe controller card, but got tired of fiddling with using other systems to reflash the firmware and then having to mask off pins on the PCIe connector to get the system to even POST.
I replaced all the "factory" fans, as well as the two on the back of the hotswap drive modules, with Noctua equivalents.