Fine Leather Belt

About 7s 0c on Beta · Horde (3 hours ago), 9s 0c on Beta · Horde (20 hours ago), and 9s 0c on Beta · Alliance (21 hours ago), from player scans. A vendor pays 1s 25c, so the auction house pays 5.3× more.

1 recipe: Dark Leather Belt.

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 6s 65c there, against 1s 25c at a vendor.