The vendors are not the real problem...
Since this Spring importing Daylilies ( and a lot of other plants) into Europe is prohibited, unless a certificate is provided that proves that the plants are not contaminated with certain pests..
Most official nurseries in the US are willing to provide that certificate, but the costs for it are around $100
And most have an minimum order limit of several 100 dollars...
So it is not impossible, but quite expensive to order from the USA