Flash Powder

About 2s 40c on Beta · Alliance (28 minutes ago), 1s 50c on Beta · Horde (6 hours ago), and 2s 0c on Beta · Horde (1 day ago), from player scans. A vendor pays 6c, so the auction house pays 38× 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 45s 60c there, against 1s 20c at a vendor.