I had one of those bought for us by family and it came from Walmart. Assembly was actually fun for me, instructions sucked! Most of the material was to thin for my liking, I would have used bigger lumber and just bought plans to build my own, but, the kit went together smooth and all the hardware was adequate.
I ended up staking ours down with concrete forming stakes that I drilled to accept the existing hardware and drove into the ground at a 45* angle. I have swung on ours and it doesn't move anymore! The stakes that the kit came with would have worked in a grassy lawn but would have never worked in our rocky dirt in Havasu.