greenhouse Anyone have any green house plans?

I looked at greenhouse's in lowes, home depot, and some hardware stores close to me. All of them had very small greenhouses with a very big price. Like 2ftx3ft is $80. I'm not willing to pay that much for a greenhouse that probably wont even stay up for a long time and will not even hold a good amount of plants. So I decided to build one on my own. Does anyone have any plans for one? I have about $200 to spend on it. Thanks!
I have had 2 of these for 3 years. I use my own shelving in them.