I've wanted a greenhouse for years, but cost of structure and operating (heating) have always detered me. Now, I'm getting the bug and having a hard time resisting. Does anyone recommend any supplier in the midwest to keep shipping down? Also, any specifics to avoid or 'must have' features I need to be aware of? I'm thinking mainly for starting plants or even some late winter tomatoes & cukes eventually.

I was doing an energy audit yesterday at a young couple's home that had a small greenhouse attached to the garage. Owners said they don't use it and have no plans to do so in the future. Theirs was something thrown together using single pane glass and relatively poor workmanship and not even worth trying to talk them out of. But, it sure got me worked up on the idea again. I may have access to used double pane patio doors that might work out OK and I could just design around them. I have no intention of having glass for the roof, just south wall & maybe east. I may tilt them at a slight angle and support the center of the glass somehow. Any advice is appreciated.