BuyDig via eBay offers the Seagate 4TB Central Network Attached Storage External Hard Drive, model no. STCG4000100, for $104.99 with free shipping. That's the lowest total price we've seen for any 4TB NAS without rebates, plus it's a current low for this model by $24. This PC/Mac-compatible NAS connects to your wired or wireless router for backup or file sharing.