Heavy Sharpening Stone

About 11s 25c on Beta · Horde (5 hours ago), 12s 5c on Beta · Horde (22 hours ago), and 8s 0c on Beta · Alliance (24 hours ago), from player scans. A vendor pays 40c, so the auction house pays 26.7× 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 20 brings about 2g 13s there, against 8s 0c at a vendor.