I purchased a 6X8 greenhouse kit this summer from Harbor Freight (350.00 on sale) It was to replace a 6X6 (500.00) one that I have had for ten years because I needed more room. My first greenhouse kit was bought from Greenhouse Megastore.
Neither of the greenhouses had great directions, but there are videos on YouTube that are VERY detailed and helpful in constructing these kits and that's what we used. Both went together pretty easily with that help. Take a look online and see if they put your mind at ease.
As for the quality of the kits...the first one was surprisingly sturdy and tight...never had a problem with it in the years I used it. The new one has a few design flaws...poor insulation around the front door and a few small gaps here and there, but nothing some caulk and insulating tape can't fix. For the price I am very happy with it.
I have a heater on a timer for some of our cold nights...no problem.
I use my greenhouse mostly for cactus as well though I do start seeds and cuttings in it.
Don't know how I got along without it for so long! Go for it!
