Emmer Brothers Cedar, Belgrade, MT is an option. 'Not sure how pricey? But they likely have anything you need.
I built mine about 15 years ago from rough cedar and Douglas Fir. I hit it with stain about every three years, but I can't tell any difference in the how the two woods have lasted so far, it looks brand new with no bug or rot issues. We're in Northern Utah.
The county had a bunch of playground equipment built from DF , old linseed stain under the brown. I was ordered to remove it all for the "new" crap,plastic. I removed it all and instead of filling a dumpster I loaded it into my tacoma after work a little at a time. I built a bunch of patio furniture and 2 pergolas for friends.
I took out some old DF 4" x 8" bridge decking that was starting to be unsafe. It had never been stained and probably 25 years old. I salvaged some of the nicer sections to resaw and it made some nice wood for paneling. You can see on the right where it was starting to rot around the fasteners. Friend that helped me made a nice fence out of his wood.
We had access to the Venice Pier wood that came down in 69'. I helped swim some beams to the beach.
How far apart will your 1x1s be spaced?
It doesn't take a solid roof to hold a snow load. If he's going to alternate 1x1s, as is often done for shade, they'll hold snow just like if it's a solid roof. Neither mine or my buddies (pics above) have roofs, but both had literally feet of snow on them this year. It just depends how close to each other the 1x1s are.
