Dood, build your own.
i'm using the highpoint rocketraid 2320 card (8 port sata 300), on an asus A8n32-sli motherboard (dual gigabit onboard). run of the mill 100.00 amd processor since it doesn't do anything but serve files, cheapest pci vid card i could find.
initially i put 4 500 gig western digital wd5000ys drives in there in raid five, i just put another drive in there and using it's OCE online capacity expansion pumped up the raid five array to a cool 2 terabytes.
future expandability was key when i made the box, so it's in a 12u server case (had on ebay for 150.00)
the drives right now are going for 170 on zipzoomfly.com
case : 150
highpoint card : 275
processor : 100
ram : 100
power supply : 100
video card : 50
80 gig sata drive for OS : 60
system without drives = 835
5 500 gig drives at current price = 850
total cost for 2 terabytes fault tolerant storage = 1685.00
best part, i can continue to add drives into that system. the case can house 26 drives total. if i were to fill out the box tomorrow i can add another power supply to drive more drives, two more 8 port cards, and 19 more drives for something around 10+ terabytes of storage. and those drives can be added one at a time to increase storage as needed.
hell, gimme 4 grand and i'll make you one ;)