ZetaWorlds

US $11 (10 Euro) per month for a 15,000-prim region on the hypergrid-enabled ZetaWorlds grid.

Other region sizes also available, including 20 Euros for a 50,000-prim two-by-two varregion and 35 Euros for a 100,000-prim three-by-three varregion.

Full pricing details here.