I haven't checked in with either Gibertie's (http://www.gilbertiesherbs.com/index.html) or North Creek Nursery for quite a few years, but they have done a fair number of Salvias over the past.

Gibertie's is in Connecticut, so they may also be in a bad way. Other large local nurseries may be able to supply some smaller garden centers (say within a metro area).

A quick scan of some nurseries I know of wasn't fruitful. I remember Blue Meadow Herb Farm in Montague, MA, but that was an exceptional nursery.

Here is a link that might be useful: North Creek Nursery