Sorry, I don't have plans, but I'm curious. What type of greenhouse are you looking to build? What temperatures will you be keeping it at over winter?

I'd like a greenhouse too, but would only use it to store one-zone warmer plants over winter. And I would probably not heat it at all. Bascically use it as a large cold-frame. And, in the early Spring, I would use it get the tropicals (plumerias, etc.) growing before the weather warms up enough to set them out.

To be honest, I really do not know (at this time) about temps, etc. Right off hand I am thinking of keeping it in the 50's. I am not much of a handy man, so the easier the better :)I would like to build something about 8'x 8' and wooden frame.

http://westsidegardener.com/howto/hoophouse.html

gives information about constructing hoophouses, which are very cheap to build, though you may want to check your local regulations regarding any greenhouse. The PVC can be purchased at Lowe's or HD and cut with a hacksaw to create the desired lengths, which may be adjusted to fit your allocated space (hint--pi comes in handy with the calculations if you want to keep the top semi-circular). Plastic sheeting may be purchased at hardware stores or Dollar General--multiple layers of plastic are better than one for the R-value, and other translucent materials may be added as well. Harbor Freight sells awesome clamps that work well for keeping the sheets in place during high winds:

http://www.harborfreightusa.com/usa/itemdisplay/displayItem.do?itemid=94923&CategoryName=&SubCategoryName=

Harbor Freight also sells a few cheap greenhouses that have received good reviews--search for HFGH or related terms on GardenWeb for details. Sam's Club and Costco also sometimes sell greenhouses, but the online reviews are often bad. There are small pop-up and plastic-covered portable greenhouses that sell for $25-200 or so, but it's difficult to build any real greenhouse for less than $300-500.

Heating of greenhouses or hoophouses may be active or passive, using lights, thermal mass, heaters, and/or thermostats for temperature control--there are many options depending on your needs and budget. Remote thermometers from Oregon Scientific or other manufacturers are useful for keeping tabs on your temperatures to avoid chilling or overheating in the greenhouse or hoophouse, and internal temperatures may be cross-referenced against other outdoor readings to check the efficacy of your insulation and heating methods.

You realy have to watch those hoop houses made of pvc yes they are cheaper, but there is nothing more heartbreaking then arriving home from work and seeing all your plants crushed by a pile of snow, and all you can see is what used to be your green house and all your plants dead or severely damaged. If you get lots of cold weather i would not recommend pvc ! it just can't hold the snow.. Take it from someone who knows... But i will suggest cattle or hog panel.

Yes, snow is an issue if you get a lot of it--haven't had that problem in years. If the clips and the rigid internal sections that go through the crosspieces are inadequate, you can brace or reinforce the roof with wire mesh, use vertical supports for the arches, or look at some of the other options instead, such as the HFGH. Although Sam's and Costco carry some greenhouses with bad reviews, some of their higher-priced models should be good, and they do carry the exquisite-looking Victorian greenhouses from the Belgian company Janssen. Also, if your requirements are flexible, there may cheaper options on Craigslist, Freecycle, or eBay.

http://www.ericsprojects.com/?page_id=228

features a cattle panel greenhouse. This could be a stronger option for snow, but you probably wouldn't want to tear it down in the spring like you would a hoophouse.

Building one like Topher would probably be the least expensive that would last,mine with materials was less than $150 but I don't think it would last to long.I would suggest looking on e-bay,there is an interesting one that you may like that I think would last and is not to expensive,just getting the plastic on would be the only difficulty that I can see,pretty cool though,check it out-Geodesic dome

Here is a link that might be useful: Dome g/house