Cheapest NAS Solution?

Well, whats the cheapest NAS solution?  I need at least 2 hard drive slots.  Would the cheapest solution be to build one?  or is there some other alternative?  I would like price to be a maximum of 300.  Only looking to have 2 TB of storage.

 

I cobbled one together with extra/old parts and run it off freenas on an old 2 gig usb2.0 stick.  Not the snappiest, but works just fine. A pair of 3 terabyte hdd's in raid was the only actual cost for me...