I purchased a 16x24 Atlas Snow Arch GH. They have many types, and it has held up well in all winds over the last 6-7 yrs.

Some questions that will help you with your decission.

What do you want to grow, how hot do you need to keep it in winter, What will you use to heat, and how much can you afford to pay to heat. Will you run water underground to the GH, electricity ?
Does your township or burough ( local gov) allow gh in you neighborhood - Some require building permits.
Good Luck, I enjoy mine and it does not matter how much it cost it is a grat place to be in the winter. MIKE

I would recommend making it yourself and saving the money instead of buying a kit. It is easy to do. Let me know if you have any questions regarding the construction of one.