You can find several different plans for the expanded dome greenhouse that I had built at WorldFlower Garden Domes They are easy to build and very strong. Mine is 20ft wide x 32ft long, and 13ft high. Here is a picture at night: 
and a shot of the interior before it was fully covered: 
The main problem I found with this greenhouse is the heat in the summer. When outside temps get in the 80's, the inside is easily pushing the mid-90's and the plants go dormant or grow long and leggy and won't produce.I run a large fan inside and had a misting system, but it's a losing battle, even after I added ventilation. Since you are up north, you shouldn't encounter those issues. On the flip side, it is an excellent place to protect many plants in the winter. The total price for this setup was in the neighborhood of $7000.
Another option you can look at are hoophouses. I set this one up last summer as an option for my raised beds: 
It's main purpose is to protect the raised beds from the marauding deer we have in the area. It is built from 1 3/8inch toprail, available at Lowes or Home Depot. They are easily bent with a Quick Hoops™ High Tunnel Bender and they also have a downloadable .pdf instruction file. The materials for my hoophouse came to approximately $400, but I used materials I had laying around the house for the raised beds and the manure I filled them with was free. I believe that it can be done for $700 if all materials are new. As you see, I built large square beds to avoid a lot of cutting. A better option is to build slimmer beds that extend along each side of the hoophouse. That will give easy access down the center. If you have good soil, you won't even need to construct raised beds.
If I had to do it all over again, I would have just built several hoophouses. I grew cold weather plants (cabbage, radish, brocolli, peas, and lettuce) in them by simply protecting the plants with plastic drop cloth when there was a freeze warning. You'll note that I used green 70% shadecloth on the top, which was inexpensive. If shading is needed, a 30% shadecloth is more suitable.
I'll have to wait until morning to take photo's of the hydroponic experiment. If I forget, ping me and I'll get on it. In the meantime, you can browse the Farmtek website. I used the GT80 series channel, lids, and end caps.