Wanted tree lily bulbs with double flowers pollen free

Hello, does anyone know where to buy tree lily bulbs with double flowers pollen free? I promised my friend to bring such bulbs for her as a present at the beginning of September. I have tried to find such online but all online nurseries offer delivery in October-November or in spring.
See pictures of such lilies I am looking for.
Thank you in advance for any advice.

 

Hi @Black Orchid , Thompson & Morgan sell them.

The reason you can't buy them untill later is that they are not dormant yet so cannot be dug up for sale yet.