Amazon offers the Synology Disk Station 4-Bay Diskless Network Attached Storage Server, model no. DS415play, for $335.75 with shipping. (Newegg charges the same when you order via its mobile app and use coupon code "MBLB1010".) That's the lowest total price we could find by $59. This DLNA-certified media server features a 1.6GHz dual-core proccessor, 1080p video transcoding on the fly, USB 3.0, Gigabit Ethernet, and four Serial ATA hard drives bays for up to a 24TB storage capacity.
Note: It's expected to ship within one to two months.