Basically a NAS enclosure is your best bet. They are pricey because they are essentially a cheap tiny PC.
You could buy a USB enclosure and attach it to your router (most routers have at least 1 USB connector) as a network slave, but that only will handle a single drive.
EDIT:
This WD MyCloud 2x drive is on sale for 210 right now:
http://www.memoryexpress.com/Products/MX61395