Dust of Deterioration

About 2s 0c on Beta · Horde (9 hours ago) and 10s 0c on Beta · Alliance (11 hours ago), from player scans. A vendor pays 25c, so the auction house pays 7.6× 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 38s 0c there, against 5s 0c at a vendor.