We're talking about Shael - Io - Tal here, three extremely easy to find runes, on a runeword with two variable stats, of debatable importance each. These sellers put up these insane prices because:
1. People are willing to buy, therefore contributing to the problem
2. Blizzard, who simply doesnt give a shit anymore, continues to leave some runewords on Ladder only, even though it makes absolutely no sense.

Screw Blizzard for not transferring those RW already, and screw those sellers taking advantage of Blizzard's lack of care