I agree with Sue, I would buy from any of the sellers right now in the Classifieds and Group Buys forum here:
https://garden.org/forums/view...
Amador Flower Farm is in California and has a good review:
https://garden.org/greenpages/...
Also, Schreiner's Iris Gardens is in Oregon and is now selling for daylily hybridizer Bill Maryott.
https://www.schreinersgardens....
The Lily Auction is what Marcia is referring to. Lots of people go there to buy daylilies or daylily seeds:
https://www.daylily.com/cgi-bi...
Daylilies can sell from $6 and up, depending on what year it was hybridized or supply and demand.
My zone 6 here in southern Indiana has very extreme temps too, but daylilies are pretty hardy plants and I have only lost a few over the last 15 years.
Good luck on your hunt and purchases! You can always make another post to ask about a particular seller before you buy.