If you have some growing already, then why buy any. They are easy to differentiate IMHO. So it should be fairly simple to selectively collect seeds, though 200 lbs is not within my experience.
You could also dig up plugs and transplant, but again, such large scale planting is not in my experience.
I love sweet vernal grass. I've been encouraging clumps of them to grow in my little backyard garden paths and designated areas of backyard.
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