Plans: Mighty Iron Hammer

About 8s 0c on Beta · Horde (5 hours ago), 15s 0c on Beta · Horde (22 hours ago), and 6s 0c on Beta · Alliance (24 hours ago), from player scans. A vendor pays 5s 0c, so the auction house pays 1.5× more.

No. It is in Classic Era too, with the same item level, vendor price and stack size.

Sell it on the auction house. After the 5% cut a stack of 1 brings about 7s 60c there, against 5s 0c at a vendor.