I am interested in buying a piece of land in Second Life, and was searching for information when my eye crossed the Wikipedia on real estate in Second Life.
Premium members can own land (up to 512 m² without additional fees). Owning larger areas of land incurs an additional fee (which Linden Lab calls "Land Use Fee" but acknowledges that it is often referred to as "Tier") ranging from US$5 a month up to US$195 a month for "an entire region", but in reality it is actually charged for owning up to 65536m² regardless of how many regions this land is based in. This pricing refers to "mainland", i.e., land that is on an Estate owned by Linden Lab.
There is a separate type of land known as Private Estate, consisting of one or more Private Islands or Regions, which has a completely separate set of regulations and pricing. The initial purchase of each private region can only be made by one Resident and not jointly by a group of Residents, and that Resident is termed the Estate Owner. The Owner may in turn appoint Estate or Region Managers, which may even be a Resident without a Premium Account.
Land purchased in Private Estates actually remains in the ownership of the Estate Owner as far as Linden Lab is concerned and so they will not involve themselves in disputes between Estate Owners and other Residents. This means, for example, that an Estate Owner can take back land that has been paid for and Linden Lab will not arbitrate in the dispute.
Land may be owned by a Resident without a Premium Account and without impacting on the tier level of their Linden Lab Land Use Fee. Each Private Region costs US$1675 to purchase, followed by US$295 maintenance fee for each subsequent month.
Interesting information when you are about to look for some land, and you don't have a premium account.