Best way to find out if a garden center has what you want is to simply call them and ask.
They should be able to answer the question for you.

You might want to give Russell's Garden Center in Wayland a call. Most times you will find that hard to find plant, in the gardens for sale.

Fran

At some point a couple of years ago, Lake Street Garden Center in Salem, NH had it listed. You could call and see if they have it this year.