This would help people to get their useful items back after they vendored by an accident.
A small periode till the items get cleared from the vendor and cannot be bought again would be good too, like 30-60 minutes? And it'd keep the vendors clean from trashes.
Well, this is what I've heard from someone. He once sold his level 40 boots with a radiant zirconia socketed. He forgot it had it because he was too happy for getting level 49 set and didnt care of the socketed gem warning.