I check my local feed & seed stores too. Prices appear slightly higher at times, but the savings in shipping costs more than covers it. I've learned to compare the final (including shipping and taxes) costs. Some of the online sources look cheaper... until those shipping costs get added in, plus I have to wait for the delivery vs just picking things up on the spot.
That said, along with the sources mentioned https://www.greencoverseed.com/
has done me well... aside from the shipping costs. I like their seeds and mixes.
A side note on daikons, my chickens really love their greens. I am grabbing a few leaves here and there out in the field and tossing them in the chicken tractor whenever I take a walk. The only think they prefer to those greens so far are fruit cores.
Another note, I have bought a couple 50# bags of oat seed sold as feed (and my chicken do get a share) and not germination tested. Cheap at just over $12 a bag and they sprout nicely. Just using them for cover until last frost for now. Local extension guy says oats not recommended here. Yeah, yeah... testing a few to see how they do anyway.
Oh, I took a pic today: some rows of those oats with rows of field peas between. They were planted about 10 days ago.