Welcome to PTO. You should not have any problem finding buff Orpingtons (and many other colors) in your area. I have some Orpington hens in my flocks ( lavender, lemon lavender and even a lavender splash) and I acquired the last four of them from local egg stock and I am in the Milton area. They are lovely, friendly, docile girls and pretty reliable winter layers.
If you check through the site you should come across the ‘coop plans’ section that should have lots of good ideas for coops and pens for all budgets. Some people have been very imaginative and crafty about repurposing building materials or items as building coops from scratch can get very expensive. All of us on here have had to go through some sort of learning curve so it is nice to learn from other people’s mistakes as you can’t ( and your chickens won’t) live long enough to make them all yourself!

If I have a few pieces of advice to give they would be:
1) if you can do so try to actually visit one or two hobby farms/ chicken coops to see ( and feel and smell etc) the pros and cons of their set up. It will give you a little dose of the reality of it before you start to invest and build.
2) Be as generous as you realistically can be with your budget to build as solid a coop as is feasible if you are planning to be keeping chickens for any length of time. A well made coop will not come cheap unless you are extremely lucky and can get a well made ( and properly cleaned) one second hand.
3). If you are building your own coop then do: put in proper screened windows (that open and close), ventilation ( ridge vents etc) and insulate the coop. This can be even more important in the summer than winter as most chickens do not do well with our hot humid summers.
Good luck with your chicken and coop search!