If you are looking for cost-effective alternatives to Second Life (@ 300 USD/Month), with full administrative control and excellent customer support, I recommend Dreamland Metaverse (@ 45 USD/Month). Dreamland Metaverse is recommended as an Editor’s Pick by Hypergrid Business.
Using the Imprudence Viewer, you can upload selected items (.xml files) or entire sets of items (.iar files) from OS "freebie" sites. Linda Kellie’s site, for example, includes Animals, Animations, Attachments, Buildings, Clothing, Food & Drinks, Furniture, Hair, Holiday, Plants, Sculpts, Skins, Terrains, and Textures.
Options include starting with empty land, for do-it-yourselfers, or a free-of-charge, pre-built "Universal Campus" (see picture). You can have your region be connected to the hypergrid, to visit other owner regions, or standalone. Regions are offered for US$ 30, 45 and 90, depending on how much memory your region needs (512 MB / 12,000 prims, 1024 MB / 24,000 prims or 2048 MB / 45,000 prims). The standard OpenSim region for US$ 45 is the most popular region.
Universal Campus image courtesy: Siterma