An order for an Openspace consists of 4 low prim regions for the same price as a normal Private Island - so USD$1250 initial fee followed by USD$195 per month thereafter. You cannot buy 2 or 6. They come in sets of four per order.
why would any one order open space and still pay the same as a regular private island and get so few prims to use.
honestly if i wanted open space around my islands i would just buy a regular private island and leave it open.
if I'm reading the announcement wrong i apologize
EDIT:
my apologies are extended i Indeed read the announcement wrong.
i have found out the initial cost is for 4 open space sims not one as i had been thinking.