I'm thinking:

Archaic Key - 500 Tabs
"A forbidden key from a lost era"
(Opens Locked Treasure Caskets)

Or even cooler would be for something like 20,000-30,000 Tabs, let us buy the special unique Casket Item from the area i.e Smithy Torque, Wizzan Grip, Proeusse Ring etc..

I have 50,00 tabs, and have nothing to spend it on except 50 Tabs here and there for Repatriation.