I think most people who garden with native plants still buy plants that aren't native whether they're for their yards or inside their homes.
1) What percentage of native plants that you buy are locally native?
From the county where you garden and documented as having occurred naturally in your county should be close enough for this question.
2) Native to your side of the Rockies and within say a 100-150 mile radius of where you garden?
Try as I might I rarely can find locally native plants unless I'm buying them from a spring plant sale hosted by a local native plant society or if a neighbor is sharing with me. My guess is I'm buying 25% or less.
Plants that are indigenous to within a 100-150 mile radius are becoming a lot easier for me to get my hands on these days as there are many native plant nurseries popping up. Best guess is I'm in the range of at least 50% in this category.
The remaining 25% I buy is a mish mash of non-natives including cultivars of native plants, plants indigenous to different regions of the Eastern US, mild mannered non-natives that are indigenous west of the Rockies, and mild mannered plants that aren't even native to my continent. Some that come to mind that I bought would be another Japanese Maple, another peony bush, three really nice Pacific ninebarks, Amsonia tomentosa, and a boatload of slipper orchids. Did receive some Aesculus flava and Viola cucullata 'White Czar' as a gift and have planted those.
Over the years I've noticed the percentage of plants I buy that go in the ground that are native to my region going up dramatically to probably somewhere in the 95+ % range. It just sort of happened the more I worked on my property. I've begun to remove some of the exotic plants I bought and received as gifts over the years and have been replacing them with natives. The hostas I have growing here are slowly being replacing with ferns.