I was debating building a greenhouse from scratch but after I priced all the materials I decided it would be more practical to wait for Harbor Freight to have one of their sales. I looked at all the reviews on the Web and except for a handful of bad reviews, this one looked good. The instructions that come with the Greenhouse are almost useless and in a few places they are 100% wrong. I found a PDF written by a guy that bought this same Greenhouse and his instructions are way better then the ones that come with the product.
Here are a number of links that maybe helpful:
I placed my Greenhouse on a Pressure Treated frame made from 2" X 6"s. I filled the inside of the frame with Pea Gravel after laying down a tarp to stop weed growth. Many say you should use 4" X 4" for the weight but I attached my frame to the garden beds as well as to the chain-link fence. The front side that was not attached to anything I attached to a 2" X 2" staked I pounded into the ground about 2 feet. So far it has stood up to the Michigan wind. One review I read said it stood up to 60 MPH winds in Main. The Greenhouse was a bit hard to put together by single handed but it is doable. So far, I don't have a single complaint.
I added two wooden benches inside made form Pressure Treated 2" X 4"s and joined the benches together along the back wall with a solid top cover with linoleum tiles to make a Potting Bench. I also too the extra step to run water and electrical to the Greenhouse so I can add a few Low Voltage Lights that I had left over from the front yard as well as get water to my drip irrigation system in the garden.