I want a greenhouse...What's the best?
 

Here is a company near Santa Barbara that makes nice looking greenhouse kits.
Buy a greenhouse kit and build your own greenhouse from SBGreenhouse.com

For their "standard kits" they say they offer either corrugated polycarbonate glazing or 6 mm double wall polycarbonate.
standardkits.html
The price sheet though only shows options for either 4 mm or 6 mm double wall polycarbonate.

Polycarbonate is very tough, it is not likely to break. But it can deform and pop out of a frame. I would think that the 4 mm double wall and even the 6 mm double wall would be very flimsy and likely to pop out of the frame in high winds. The corrigated material might better withstand high winds but it won't give as much insulation from cold.

I used 16 mm triple wall polycarbonate but I paid probably more than $3.00-$4.00/sq. ft. for that material. This material is strong enough that I can put my full weight on the roof panels.

I would call the SB Greenhouse people and ask them about the ability of their greenhouses to withstand wind.

Here are their prices for "complete" packages that include heater, ventilation, mist, benches etc :
Specials

Here is a place that sells components if you want to build your own polycarbonate paneled greenhouse:
Multiwall Systems

David, thanks so much for the very informative note. I will follow up on that since winter is just around the corner.
Thanks again
Danny

i have the backyard pro kit from farmtek, Backyard Pro Greenhouse - FarmTek
and it has stood 80mph winds here for 5 years now...it has 6mm polycarbonate panels and they are doing fine...it has a ten year warranty on the panels and is made of aluminum framing....i am very pleased with it.....i am thinking of buying another for my okla house.....gl

I purchased a greenhouse kit from Costco at a discount. The manufacturer is SunGlo Sunglo Greenhouses They come with extras and you can build to your desires in 2.5' units. Keep in mind, if you want an 8 x 12 and that is as large an area as you have for the greenhouse, fine but if your budget and space will allow a larger unit go as large as you can.... trust me, you won't be sorry. Also you might want to consider the height of the center of the unit because some units, like mine from Sun Glo, are only 7' 6" so it can be a bit claustrophobic. I built mine up on an elevated wall which gives me an additional foot of head room. Also, unless the polycarbonate is UV treated, as most for greenhouses is, it will yellow after several years. I used acrylic which is very strong and doesn't yellow with time. Shade cloth makes a difference, also. Woven or knitted. One will unravel if it gets a tear while the other won't. Placement to extend your utilities is also a key consideration. If you need heat, are you going to use natural gas, propane or electricity and which is more costly in your area. I use natural gas because it is significantly cheaper in Michigan. A stand alone heater purchased at one of the Big Box stores has worked for me for 5 yrs now. Lots to consider before you start.

whichever one you choose, greenhouse growing is an adventure, and such a pleasure to spend time in....you will get many years enjoyment out of it....