The problem you have with aquiring back yard specs, is that then you are either planning on flying out to someones yard to get them, or relying on the person buying to be able to give you area, change in slope, ect, which is not something that is particularly easy to do. I would argue that its harder than building the stuff yourself really unless your yard is perfectly flat. I could see a pre-fab structure that would work for all flat yards of x by y yards, but as soon as you throw a slope in, all that goes to hell.
As far as stuff being solid, again with basically a circular saw, a power drill and a tape measure you can build some seriously solid stuff. Take my rail that I made, in about 3 hours with nothing but those 3 tools.
Super solid, cost I think 50 dollars not counting the 2 power tools used. I would love to hear your ideas on how to ship something this large and heavy, pre fabbed and not require it it to roll up on a flatbed to someones house. Shipping cost on that 50 dollar, 3 hours of work rail would likely amount to 100-200 dollars easily.