Flash Powder

About 1s 50c on Beta · Horde (5 hours ago), 3s 0c on Beta · Alliance (24 hours ago), and 2s 0c on Beta · Horde (1 day ago), from player scans. A vendor pays 6c, so the auction house pays 23.8× 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 28s 50c there, against 1s 20c at a vendor.