green house for over wintering tropicals?

I am looking for a small green house that I can over winter my Tropicals, around 21 total big and small.Then I want to use it to pot things up and store my garden stuff. What should I look for? I am confused as to what they say they are made of. Some look like plastic sheets covering them and then some say polycarbonate panels. What do you use? have you heard bad reviews on some? I was looking at these green house sheds too, but they wont keep things from freezing? I heard that the one from Sam's is good.I am at a loss.
Any input would be good.?

You'll be best off with one of the ones with the rigid plastic walls (polycarbonate panels). Look for ones that have at least twinwall polycarbonate, those will keep the heat in a little better. A lot of people have the Rion from Sam's club so if that's in your budget it should work fine. Also, no matter what you end up buying, you'll also want to invest in a heater if you want to overwinter tropicals, otherwise you won't be able to keep it warm enough.

I have the 8x8 Rion from Sams, and love it! I'm zone 5, and I do use a small milk house heater to keep the temp from dropping below 50º. I also line the lower walls with buckets of water to absorb daytime heat, my shelves are above them. Right now I'm collecting bubble wrap and will be adding that to the roof areas at minimum, more if I can get enough free. The GH does great except on extra windy days. We have clear caulked the joints, there were a few places where we could feel air coming in.

Last winter we had extra cold windy weather and everything survived. I love going in on winter days and smelling and cutting my herbs and spices, yum.

I keep plants in there that would otherwise die here in St. Louis' winters.

I will check that one out. I have heard others say that they like the one from Sams. I would be putting this up against the shed, so it would be protected on one side and the back will be away from the wind.

Thanks
Marie

When I go to Sam's Web Site I do not see that brand name.

You are right, I don't see that brand there anymore, sorry.

Thats ok, I did find it on the web and you can order the kit.