Naylor Creek - sends nice, mature plants
White Oak Nursery -has a great refrigerator sale in spring
Hallsons -again nice, mature plants
In the country garden and gifts - Josh is very active in American Hosta Society and knows his stuff
Made in the Shade Gardens - met him at a hosta convention, very nice people to work with
Jim's Hosta - usually more expensive than the rest, but has some rare ones you won't find anywhere else.
Land of Giants Hosta Farm - located in WI
Kuk's Forest Nursery - have never ordered online, but pick up a few from him at a convention
I am sure I have forgotten a few, but these are online sources I know to sell safe and reliable hostas.