We bought one, or rather, my inlaws bought one for dd, and it is from Creative Playthings. It's actually the exact one pictured on the homepage, except we had a few custom things done, like a built-in picnic table under the treehouse, and a two-person lawn swing.
They have a choice between chemically-treated pine, which we did not want, or natural redwood. The redwood is more expensive, but they way it works is that they have about four models of swingsets, each a little bigger and more expensive than the last, so we just went down one from what we could afford so that we could get the redwood.
We're really happy with it!http://www.creativeplaythings.com/