JBtheExplorer
Native Gardener
All you need to do is to collect seeds from the wild flowers nearby. You don't have to buy them. I am sure JB will share some tips with you.
I wouldn't recommend that, especially for as large a project as @BradinMichigan wants to do. It's also illegal, except when taking from private property where the homeowner agrees. If you do that, I'd suggest only taking seeds from a specie that has a high population, and taking very few seeds from it.
I'd recommend looking through Prairie Moon Nursery's native seed mixes. Each seed mix comes in multiple sizes, from 500 sq. ft. to an acre. They have different mixes for different conditions, e.i. wet, dry, average, shady, sunny, short grass, tall grass, etc. Their PDQ mix is a solid choice. It's one of their cheapest mixes, but also the quickest to establish. Some species start blooming in year 1.
I wish I would've used their native seed mixes when I started. I did it the hard way and bought packets of individual species. I really had no clue what I wanted or what I was doing, and I'm still finding myself working to make it better each year. A pre-made native seed mix would've helped me a lot, and some of them are surprisingly cheap for 1000 sq. ft., which is about exactly how much habitat I have right now.
I'd have to till up a lot of grass though. Maybe I'll add a small section every year.
Adding on every year is what I did. I've been doing that for four years. Started with 64 sq. ft., and as I said, now have roughly 1000 sq. ft. It's a little weird having each section in a different year of maturity, but eventually that'll even out.
Since you're in Michigan, I assume your weather has probably been as bad as mine, but if you can get any seed down, this is the best time of year to do it.