First off, welcome to permies and to
permaculture as a whole. I love when I see questions like this one.
Building styles like cob, strawbale, earthbag and rammed earth all depend on location and
local resources. If you have a local farmer cutting lots of
straw for a good price, you should narrow your search to bale and cob. Does the property you find have the right soil buildup for earthen structures, if not, then material for earthbag, rammed earth, and cob will be more difficult and more expensive to source. I will say that all of these are viable building materials, all with their own unique properties perfect for particular climates. Likewise, all of these building materials can save you thousands of dollars if you are willing to put in the labor. I've seen cob and bale houses built for as low as $3,500 and upwards to $200,000 depending on how much labor the owners put into it themselves and how much time got put into finding low cost materials.
With cold winters and warm summers, don't get hung up on one building material. All of these can be mixed and matched. Look into building a house with passive
solar gain, highly insulative bale walls, and large mass for heat storage. The sky is the limit!
Don't forget to check into local codes and see what is acceptable.
Look for natural homes built with similar style to what you want in your area and ask to see them. Most owner builders love to show off their work and will give you great pointers.