"Good NASes can get expensive, to the extent that I gave up and bought an old tower PC for 90 quid (quad-core Opteron!) and put 6 hard drives and a second gigabit network card in it. With Windows Server 2012 R2 NIC teaming and RAID6, voila: super speedy reliable access."
Or you could use FreeNAS -
FreeNAS - Wikipedia, the free encyclopedia which is free, highly capable and enjoy the pleasures of BSD and a ZFS pool with whatever old hard drives you have running around. Even a single-core system will cope quite happily if your demands are not excessive.
And FW800 is a LOT quicker than USB2 as well as daisy-chainable (you don't need a hub).
Mac